emacs-fu

update

2012-02-01T20:24:00.000+02:00

Regular emacs-fu programming will resume shortly, but for now I'll provide a brief update on some of my projects.

Recently, I discussed sauron, and event-tracking tool for emacs. I added some new features, fixed some bugs, and got some contributions (yay!)
- tweak/improve priority handling
- add a backend for the emacs-24 notification system
- add settings to make the sauron frame 'sticky', and to hide the mode-line
- enable dbus-message source outside your session; useful for cron/procmail etc.
- display events in a tabular fashion
- add support for John Wiegley's event.el
- much improved documentation
- other things…
Sauron version 0.2 is available through Marmalade (see Package Management Revisited)
I released version 0.9.8 of mu (e-mail searcher/indexer, previously discussed in Searching e-mails with Wanderlust and mu). Now, for emacs-users I've added mu4e (manual), a new & experimental e-mail client. It won't be big and professional like gnus, but it's fun to hack on, and I've been using it for a few months.

sauron: keeping an eye on what's going on

2011-12-22T00:01:00.000+02:00

I'm a fairly busy person, and need to keep track of a lot of things. That includes following a bunch of internal IRC channels, attending meetings, meeting deadlines and so on. But I don't want to stare at my org-mode calendar, or flip through ERC buffers all the time.

Instead, I'd like to have one little emacs frame (window) that gathers these ('events'), and transfers me to wherever the event came from when I click it - some IRC-channel in ERC, my org-calendar etc. and other inputs. Note, using Bitlbee, you can include Facebook-contacts, GoogleTalk-buddies and Twitter-tweets, … in ERC - so, you can track just about anything.

In addition, with so many inputs, I'd also like the possibility to filter out unwanted events, and generate various light/sound effects and fireworks, proportional to the priority of the event.

For all this, I wrote a little emacs-tool called Sauron that does just that. M-x sauron-start pops up a frame that receives events, and M-x sauron-stop hides it and stops listening. It works with ERC, org, and listens for D-Bus messages; so it's pretty easy to get events from all over the place.

It's a bit of a balancing act to get all the important information while not being swamped in noise, but Sauron allows you to fine-tune it to whatever works the best for you. I've tried to have sane defaults though, so things should mostly work without too much configuration - but if you need the power, it's there. I also added some convenience functions to make it easy to get sounds and other special effects.

So - it's brand new, it is of seems-to-work-for-me-quality, and I'd like to invite others to try it out, hack it, give feedback, add new back-ends and so on – what better Christmas present to ask for!

There's documentation, examples etc. to be found in Sauron's github repository.

system administration with emacs

2011-12-10T14:33:00.001+02:00

When performing system administration tasks, one often needs to edit files owned by root.

For both security and safety reasons, it's a good idea to do as little as possible as root (or with root privileges). For that reason, you probably don't want to run Emacs as 'root', because it's simply too powerful. I often see people use vi (usually, vim) instead – but since it allows you to do just about anything as well (like running shell commands), that's not much of an improvement.

Now, a while back we discussed editing files owned by root with tramp – you can use emacs with your normal user-account, and use sudo to write the root-owned file. That makes it much harder to screw things up.

Another reason people use vi for little editing jobs is because its startup time is significantly shorter than the startup time for a new emacs instance. For that, however, we have emacs daemon.

Combining tramp and emacs daemon and a shell function:

# edit file with root privs
function E() {
         emacsclient -c -a emacs "/sudo:root@localhost:$1"
}

Now, we can very quickly edit any file owned by root using 'E' --

$ E /etc/hosts

So, if you prefer emacs, there's little reason to use vi, even for editing system files – although I have to admit that it takes time to evict 'sudo vi <system file>' from my muscle memory.

Update reader Yi Wang mentions that, in fact, we can make this a bit more general using sudoedit; so, instead of using Tramp, we can use:

# edit file with root privs
alias E="SUDO_EDITOR=\"emacsclient -c -a emacs\" sudoedit"

This works also without absolute paths.

package management revisited

2011-11-21T22:22:00.001+02:00

Ages ago we discussed ELPA, the emacs packaging system. It allows you to
browse through an online repository of emacs packages and install, uninstall
and upgrade them, all from within the emacs comfort zone (menu:
Options/Manage Emacs Packages).

Emacs 24.1 (a pretest is available) will include a version of ELPA --
package.el; the version included with emacs 24 supports multiple
archives. The official archive is the one provided by GNU, then there is
the current one for ELPA, but there's now a third one available: Marmalade.

Marmelade ('Spreadable Elisp') offers a very easy way for developers to
make their packages available to emacs users, and an even easier way for
users to test out interesting packages.

To use all available package repositories (GNU, ELPA and Marmalade), add
the following snippet to your .emacs:

(setq package-archives '(("ELPA" . "http://tromey.com/elpa/") 
                          ("gnu" . "http://elpa.gnu.org/packages/")
                          ("marmalade" . "http://marmalade-repo.org/packages/")))

This works out-of-the-box for Emacs 24; for Emacs 23, you'll need the newer
package.el, which you can get from the emacs 24 repo (if necessary, remove
the old package.el first).

Currently, there are 870 packages listed in the three repositories – a lot of
toys to play with! In fact, it is already getting quite hard to find what
you're looking for; a bit more structured way (maybe using categories) would
be useful. Also, a bit more information than the one-line description would
be very useful.

Nevertheless, it's a great addition to emacs, which will make it much easier
to play with packages – without even having to read the installation
instructions.

quick note-taking with deft and org-mode

2011-09-15T21:49:00.001+03:00

Emacs must be gathering a lot of enthusiasts lately; there's hardly a week where I don't discover some new gem. Recently, I discovered deft. And apparently, I wasn't the only one.

So what is it deft good for? Well, often I want to jot down some quick thing during a meeting or a telephone-call. Of course, I don't want to think about file names or anything else distracting me from my task, just get me that note already! In addition, at some later time, I want to be able to quickly search through the notes I made.

For MacOS, there's a program called Notational Velocity which does this. But really - it sounds like a typical task for emacs - wouldn't it be nice to have an emacs package that does roughly the same?

And that is what deft does - enable you to quickly write notes, and retrieving them later. The author has an excellent introduction on his website, so my job is very easy :) deft is not part of org-mode, but they can work together seamlessly. Here's my set-up:

;; http://jblevins.org/projects/deft/
(when (require 'deft nil 'noerror) 
   (setq
      deft-extension "org"
      deft-directory "~/Org/deft/"
      deft-text-mode 'org-mode)
   (global-set-key (kbd "<f9>") 'deft))

This blob goes in my .emacs. Note, the first line ensures that emacs starts without errors, even when I run on a system without deft. Apart from that, I make deft use org files for note taking, which makes it all very familiar.

All notes are saved ~/Org/deft - you can set it to something else of course. A Dropbox-folder seems to be a popular choice for synchronizing between machines.

Finally, the last line binds F9 to deft-mode. So, when I need a quick note, I can type F9 C-c C-n and start writing.

finding just about anything

2011-09-08T23:22:00.000+03:00

Buffer-switching is one of those things I do all the time in Emacs. And it should be quick and efficient, or it will break my 'flow'. There are many ways to customize the buffer switching experience, and we already discussed quite a few of those here: using Ctrl-Tab, iswitchb/ido, ibuffer, the lusty explorer and others.

Some of those packages - ido and lusty-explorer - do not solely focus on buffer-switching - they also let you open files using the same user interface. But why stop at files and buffers - wouldn't it be nice if we could quickly find just about anything quickly?

Indeed that would be nice - and there's a way to do just that - using the aptly named anything package. I was always a bit put off by this package due to the screenshots (see link), but once I got over that, I've become a very happy user.

Anyhow, what can anything find? I mentioned buffers and files, but it can also find bookmarks, recently used files, any file on your system (using locate), man-pages, info-pages, emacs-function/variables, FIXME-comments, org-headlines, bbdb-contacts, google-suggests… and a million other things. It can probably find your car keys, too.

Installation is pretty straightforward, using the git-repository:

git clone git://repo.or.cz/anything-config.git

Then, go into the just-cloned directory and execute make. After that, add to your .emacs (or ~/.emacs.d/init.el):

;; path-to-anything is the path which has the 'anything' we just cloned
(add-to-list 'load-path "path-to-anything")
(require 'anything-config)

This will add a menu with various anything-commands, and a bunch of key-bindings, starting with F5. Play around a bit with it, it's nice. The results are shown in a little temporary buffer, and pressing Tab will let you do (search-type dependent) actions on the matches - for example ediff two buffers.

Of course, the real fun starts when we super-charge some of the normal emacs functions with anything-based ones. Let's look at buffer switching. Let's create an anything-based version, and assign it to C-x b, the good-old switch-to-buffer.

The thing to consider is that while anything can find just about anything, you (well, I) usually only want to search for a certain set of things; when I want to switch to another buffer, I don't want to match man-pages. Luckily, anything allows for making nifty function which use certain subsets of the search sources. So for buffer switching, I have:

(global-set-key (kbd "C-x b")
  (lambda() (interactive)
    (anything
     :prompt "Switch to: "
     :candidate-number-limit 10                 ;; up to 10 of each 
     :sources
     '( anything-c-source-buffers               ;; buffers 
        anything-c-source-recentf               ;; recent files 
        anything-c-source-bookmarks             ;; bookmarks
        anything-c-source-files-in-current-dir+ ;; current dir
        anything-c-source-locate))))            ;; use 'locate'

This will search in buffers, then in my recent-files, then in my bookmarks, the files in the current directory, and finally check with the locate tool. That last one is pretty neat, and finally gives me something back for the countless times I've wondered why the hard disk is grinding – indeed, it was locate, updating its database.

Then, I've defined another binding for searching general documentation on my system; I've put it under C-c I. This looks look something like the following:

(global-set-key (kbd "C-c I")  ;; i -> info
  (lambda () (interactive)
    (anything
      :prompt "Info about: "
      :candidate-number-limit 3
      :sources
      '( anything-c-source-info-libc             ;; glibc docs
         anything-c-source-man-pages             ;; man pages
         anything-c-source-info-emacs))))        ;; emacs

These are sources I query quite regularly; there are many more to be found - for most packages with info-pages there's a corresponding anything-c-source-info-...; there's a list in anything-config.el.

Now, those are my general documentation sources; in specific modes, I have specialized information sources; for example, for elisp-mode:

(add-hook 'emacs-lisp-mode-hook
  (lambda()
  ;; other stuff...
  ;; ...
  ;; put useful info under C-c i
    (local-set-key (kbd "C-c i")
      (lambda() (interactive)
        (anything
          :prompt "Info about: "
          :candidate-number-limit 5
          :sources
          '( anything-c-source-emacs-functions
             anything-c-source-emacs-variables
             anything-c-source-info-elisp
             anything-c-source-emacs-commands
             anything-c-source-emacs-source-defun
             anything-c-source-emacs-lisp-expectations
             anything-c-source-emacs-lisp-toplevels
             anything-c-source-emacs-functions-with-abbrevs
             anything-c-source-info-emacs))))

This post just scratches the surface of what is possible – so go and experiment :) One interesting thing is to add your own sources; I played a bit with that already,

There are many things in anything I did not cover yet. First, there are many more sources to search - and it's pretty easy to write your own – see the EmacsWiki-page.

customizing the mode-line

2011-08-25T23:48:00.001+03:00

The mode-line is the emacs 'status bar', the bar just above the minibuffer that shows various pieces of information, such as the buffer name, the major mode, maybe the current line number, some indicators for active minor modes, and so on. As I'm looking at it, it starts with 1<U:**- (which is: input-method: latin-1-alt-postfix, buffer-coding-system: utf8-unix, line-ending: unix-style, buffer is writable and buffer is modified – the tooltips help).
As with just about anything in emacs, the mode-line can be customized just the way you like. I give some example below, not because I think it is necessarily the best way, but just to give you a bit of an example to start with when making your own best-mode-line-ever.
I'm not going through all the details of the example, but let me highlight a few things that make it a bit easier to understand.
First of all, the mode-line can be customized by setting the variable mode-line-format; this variable becomes buffer-local automatically when changed, so if you want to set it for all buffers, you'll need to use setq-default in your .emacs (or equivalent). The format is quite similar to the one for frame-title-format, which we discussed in setting the frame title a while back.
mode-line-format is a list of items which are evaluated, and put together as a string which then ends up as the mode-line contents. These properties can be any string. The following types of items can be used:

First, normal strings are just shown as-is;
Then, there are some special format parameters which will be replaced with their value in the mode-line, from the Emacs-documentation:

  %b -- print buffer name.      %f -- print visited file name.
  %F -- print frame name.
  %* -- print %, * or hyphen.   %+ -- print *, % or hyphen.
        %& is like %*, but ignore read-only-ness.
        % means buffer is read-only and * means it is modified.
        For a modified read-only buffer, %* gives % and %+ gives *.
  %s -- print process status.   %l -- print the current line number.
  %c -- print the current column number (this makes editing slower).
        To make the column number update correctly in all cases,
        `column-number-mode' must be non-nil.
  %i -- print the size of the buffer.
  %I -- like %i, but use k, M, G, etc., to abbreviate.
  %p -- print percent of buffer above top of window, or Top, Bot or All.
  %P -- print percent of buffer above bottom of window, perhaps plus Top,
        or print Bottom or All.
  %n -- print Narrow if appropriate.
  %t -- visited file is text or binary (if OS supports this distinction).
  %z -- print mnemonics of keyboard, terminal, and buffer coding systems.
  %Z -- like %z, but including the end-of-line format.
  %e -- print error message about full memory.
  %@ -- print @ or hyphen.  @ means that default-directory is on a
        remote machine.
  %[ -- print one [ for each recursive editing level.  %] similar.
  %% -- print %.   %- -- print infinitely many dashes.
Decimal digits after the % specify field width to which to pad.

Forms of the type (:eval ...) are evaluated each time the mode-line is drawn (just like the '%'-parameters) ; so, if you have a value that changes of the course your emacs session, you should use (:eval ...). For example, for your emacs-uptime you could use (:eval (emacs-uptime "%hh")); while the emacs-PID does not change, so simply you could simply use (format "PID:%d").
The format parameter mentioned above are of evaluated each time as well. Note that you have to be a bit careful with evaluations - don't do too heavy operations there, and be careful the updates don't recurse.
There are many others which I won't go into now - please check the Elisp reference. It's a rather baroque format…

Now, let's put this all together in an example (tested with emacs 23 and 24). As I said, this is for demonstration purposes only; but hopefully it gives you some inspiration. A lot of the 'magic' (colors, tooltips, faces) happens with the propertize function; again, the Elisp documentation can tell you a lot more about that. I'm (ab)using the various font-lock-faces to have colors that blend in nicely with your current theme.
And it has a limitation still, namely that it does not react to mouse clicks; how to that, I will discuss in some future article.

;; use setq-default to set it for /all/ modes
(setq mode-line-format
  (list
    ;; the buffer name; the file name as a tool tip
    '(:eval (propertize "%b " 'face 'font-lock-keyword-face
        'help-echo (buffer-file-name)))

    ;; line and column
    "(" ;; '%02' to set to 2 chars at least; prevents flickering
      (propertize "%02l" 'face 'font-lock-type-face) ","
      (propertize "%02c" 'face 'font-lock-type-face) 
    ") "

    ;; relative position, size of file
    "["
    (propertize "%p" 'face 'font-lock-constant-face) ;; % above top
    "/"
    (propertize "%I" 'face 'font-lock-constant-face) ;; size
    "] "

    ;; the current major mode for the buffer.
    "["

    '(:eval (propertize "%m" 'face 'font-lock-string-face
              'help-echo buffer-file-coding-system))
    "] "


    "[" ;; insert vs overwrite mode, input-method in a tooltip
    '(:eval (propertize (if overwrite-mode "Ovr" "Ins")
              'face 'font-lock-preprocessor-face
              'help-echo (concat "Buffer is in "
                           (if overwrite-mode "overwrite" "insert") " mode")))

    ;; was this buffer modified since the last save?
    '(:eval (when (buffer-modified-p)
              (concat ","  (propertize "Mod"
                             'face 'font-lock-warning-face
                             'help-echo "Buffer has been modified"))))

    ;; is this buffer read-only?
    '(:eval (when buffer-read-only
              (concat ","  (propertize "RO"
                             'face 'font-lock-type-face
                             'help-echo "Buffer is read-only"))))  
    "] "

    ;; add the time, with the date and the emacs uptime in the tooltip
    '(:eval (propertize (format-time-string "%H:%M")
              'help-echo
              (concat (format-time-string "%c; ")
                      (emacs-uptime "Uptime:%hh"))))
    " --"
    ;; i don't want to see minor-modes; but if you want, uncomment this:
    ;; minor-mode-alist  ;; list of minor modes
    "%-" ;; fill with '-'
    ))

Have fun playing with this!

toward balanced and colorful delimiters

2011-05-16T22:59:00.001+03:00

Emacs has the very useful feature of blinking the corresponding left "(" when you type its partner ")" (and the same for other delimiters like "[]", "{}" etc., depending on the mode). This is very useful for programming, especially for languages like Lisp and Scheme and the like.

Further help can come from tools like autopair or paredit – although the latter is a bit too much bondage & discipline for me, many people love it.
Anyway, recently I discovered a new helper in the quest for balance in delimited universe: rainbow-delimiters. With this package, the delimiters all get different colors based on their nesting level. It works wonderfully well.
Installation is straightforward:

download rainbow-delimiters and put it in your load-path
add something like the following in your .emacs:

(when (require 'rainbow-delimiters nil 'noerror) 
  (add-hook 'scheme-mode-hook 'rainbow-delimiters-mode))

That's it – of course you'll need to do the equivalent for modes where you'd like to enable it. See the screenshot below – maybe a bit too colorful for some people, but I like it and I have found it actually useful to see the corresponding delimiters without having to move the cursor over them.

I already added some nice Zenburn colors for this to the Zenburn theme for Emacs-24, as can be seen in the screenshot.

porting the zenburn theme to emacs 24

2011-05-08T12:05:00.000+03:00

Just a small note: I already mentioned the zenburn color theme a couple of times. I have now ported the full (big) set of customizations to the emacs-24 format – find it at github; so if you run emacs 24 (the development version) and enjoy zenburn like me, you can give it try. Suggestions, additions are welcome.

Note, there seems to be a limitation with the :inherit-attribute for themes – in practice it means that some aspects of the theme may not work if a package sets the face before the theme does. Therefore, best to load the theme early from your .emacs or init.el; or alternatively visit the theme file (zenburn-theme.el in this case) and evaluate the buffer.

nice-looking pdfs with org-mode and xetex

2011-04-12T20:57:00.000+03:00

I've discussed the wonderful org-mode here a number of times already. It has become a pretty important part of my overall workflow. One thing I am using org-mode for, is to produce all kinds of PDF-documents that I can share with other people.

org-mode & LaTeX

In the past, I often used straight LaTeX for such things; I wrote my thesis with it, but also many other documents. There are many things I like about LaTeX, one of them being that I can use emacs for writing. Still, there are also a few things I do not particularly like. First, I think LaTeX is quite heavy with formatting directives, which hinder my writing flow (e.g., when I want to include an image, a table or a source code snippet). Another thing is that I find the default LaTeX styles a bit boring. Nothing wrong with it, but there just too many documents with the exact same lay-out.

Now, back to org-mode. One way to use org-mode is as a friendly way to generate LaTeX (and, consequently, PDFs). This is a big improvement! Much more than LaTeX itself, org-mode allows to focus on the contents of the document, rather than instructing LaTeX what to do. This comes at the price of small bit of flexibility, but, if needed org-mode allows you include straight LaTeX when needed – so while keeping easy things easy, hard things are still possible. The latter does require a bit of experience with LaTeX a though.

setting up XeTeX

Now, for the second issue, the way documents look, there are other solutions, and they live on the LaTeX side of things. I'm sure many have seen The Beauty of LaTeX. Using the XeTeX implementation of LaTeX and the fontspec package, you can create LaTeX documents with a bit 'refreshed' look.

So, the steps to get this working with org-mode:

install the texlive-xetex packages on Ubuntu and Debian (this installs a huge set of packages)
install the SIL fonts (I'm using ttf-sil-gentium and ttf-sil-charis, but there are more)
I'm also using DejaVu Mono (ttf-dejavu)

teaching org-mode about the new XeTeX stuff

We now need to define some LaTeX document class for org-mode that uses XeTeX and some of these new fonts. Let's call the document class djcb-org-article (as I often use the djcb- prefix for my own stuff), it could be something like the following (add to your org-setup – e.g., in your .emacs, make sure there is a (require 'org) before this:

;; 'djcb-org-article' for export org documents to the LaTex 'article', using
;; XeTeX and some fancy fonts; requires XeTeX (see org-latex-to-pdf-process)
(add-to-list 'org-export-latex-classes
  '("djcb-org-article"
"\\documentclass[11pt,a4paper]{article}
\\usepackage[T1]{fontenc}
\\usepackage{fontspec}
\\usepackage{graphicx} 
\\defaultfontfeatures{Mapping=tex-text}
\\setromanfont{Gentium}
\\setromanfont [BoldFont={Gentium Basic Bold},
                ItalicFont={Gentium Basic Italic}]{Gentium Basic}
\\setsansfont{Charis SIL}
\\setmonofont[Scale=0.8]{DejaVu Sans Mono}
\\usepackage{geometry}
\\geometry{a4paper, textwidth=6.5in, textheight=10in,
            marginparsep=7pt, marginparwidth=.6in}
\\pagestyle{empty}
\\title{}
      [NO-DEFAULT-PACKAGES]
      [NO-PACKAGES]"
     ("\\section{%s}" . "\\section*{%s}")
     ("\\subsection{%s}" . "\\subsection*{%s}")
     ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
     ("\\paragraph{%s}" . "\\paragraph*{%s}")
     ("\\subparagraph{%s}" . "\\subparagraph*{%s}")))

Of course, this can be customized to your own preference; e.g., North-Americans may not be using A4-paper.

org-mode takes care of the export from its own format to LaTeX, but we need to tell it to use xelatex to process the LaTeX to PDF:

(setq org-latex-to-pdf-process 
  '("xelatex -interaction nonstopmode %f"
     "xelatex -interaction nonstopmode %f")) ;; for multiple passes

That's all that's needed on the setup-side.

creating a document

Now, let's create a little test document, test.org, to show how it works:

#+LaTeX_CLASS: djcb-org-article
#+TITLE: My little document

* Introduction
  
  This is my document. There are many like it, but this is mine. It's easy to
  write without *too* _many_ /distractions/.
  
** Normal distribution

   Probability density of the normal distribution, using familiar TeX notation
   for formulae:
 
   $$\frac{1}{\sqrt{2\pi\sigma^2}}e^{ -\frac{(x-\mu)^2}{2\sigma^2} }$$

** Some table

| *Greek God* | *Roman God* | *Element*      |
|-------------+-------------+----------------|
| Zeus        | Jupiter     | Sky and clouds |
| Hera        | Juno        | Family         |
| Poseidon    | Neptune     | Sea            |
| Hades       | Pluto       | Underworld     |

We can export this to a PDF using C-c C-e p (or C-c C-e d to automatically open the PDF in a PDF-viewer). This should all work nicely; if it doesn't, note that when exporting, say, test.org, org-mode will create a file called test.tex, and visit in a buffer. There's also a buffer with the output from various commands, but sometimes it can be useful to run LaTeX (xelatex in this case) on the file by hand, to find any problems. The wonderful org-documentation about exporting to LaTeX has more information.

I think the result is pretty nice – it stays true to the class LaTeX article class, but freshens it up a bit with some news font. If you can make something better – which is not unlikely – you are of course invited to contribute your own!

Concluding

org-mode is a pretty convenient way to write nice-looking PDFs. Combined with xelatex, they don't have to look too plain :). However, I'm aware of my limitations when it comes to the coolness/aesthetic aspects, but I hope others can show the way here.

Maybe org-mode could ship with a number of ready-made templates to make it easy to make nice-looking documents, resumes, reference cards, reports, meeting notes and so on.

searching e-mails with wanderlust and mu

2011-03-31T21:10:00.002+03:00

I have discussed the Wanderlust e-mail client a couple of times already. I'm still using it, so I keep on learning new tricks. Even though there has been quite a bit of action in the competing gnus e-mail client, for my particular use-case, Wanderlust is still the best option.

'My particular use-case' consists of storing my mail in Maildirs, which I fill with either offlineimap (which has fortunately found a new maintainer) or fetchmail.

mu

When dealing with e-mail, one particularly important feature for me is the ability to search my messages. In fact, it's so important for me that I wrote some software to do this for me; the software is called mu; it indexes the messages in my Maildirs, and then allows for searching them using queries, based on message contents, headers, or other message properties.

mu works through a command-line interface, although there is an experimental GUI available as well. The command-line interface makes it possible to hook mu up with various mail-clients, such as mutt, or Wanderlust. Some Linux distributions ship mu, but since the versions they ship are often a bit outdated, I recommend building it yourself from the sources linked on the mu website. The process is fairly straightforward; and there is plenty of documentation in the form of man pages.

mu and wanderlust

I've been combining mu and wanderlust for a while (see mu and wanderlust - the old way, below), but this week Sam B. on the mu mailing list showed a way to do so in a much more elegant way - using virtual or query folders.

How does this work? Well, after installing mu, add the following to your Wanderlust setup file (~/.wl or it's moral equivalent – see the older Wanderlust posts for the details):

(require 'elmo-search)
(elmo-search-register-engine
    'mu 'local-file
    :prog "/usr/local/bin/mu" ;; or wherever you've installed it
    :args '("find" pattern "--fields" "l") :charset 'utf-8)

(setq elmo-search-default-engine 'mu)
;; for when you type "g" in folder or summary.
(setq wl-default-spec "[")

So, to start with the last part, whenever you type g in folder or summary, in the mode-line you will get something like Folder name (.inbox): [. Now simply type your mu search expression and press Enter, and wanderlust opens a (temporary) folder with the search results. Brilliant!

Next, to add virtual folders for searches you do often, simply add some folder specifications like the following to your .folders file (again, check the older Wanderlust posts if you're not familiar with folders-file):

VFolders {
# message I received today
  [date:today..now]!mu  "Today"

# messages bigger than 1Mb  
  [size:1m..100m]!mu    "Big"

# signed messages i got in 2010 related to emacs
  [date:2010..2011 flag:signed emacs]!mu "Signed-Emacs2010"

# unread messages
  [not flag:seen]!mu    "Unread"
# or (for mu  >= 0.9.4):
# [flag:unread]! mu      "Unread"
}

After this, restart Wanderlust, and there you go! Wanderlust will display your brand new virtual folders with an icon that looks like a little whale.

You can put arbitrary mu search expressions between the [], matching whatever is useful in a certain case. Check the mu documentation to see how to do this.

Note, the messages you get in these virtual folders are links to the original messages. In practice, this means that changes you make to the links do no affect the originals – if you delete a link you're not deleting the message.

mu and wanderlust - the old way

This discussion would not complete without a description of the old way I used search. This method may still be useful for integrating mu with other clients such as mutt.

What I've been using for a while is a (in retrospect) rather clumsy way to integrate message searches with Wanderlust: based on the results of a query, I would create some special Maildir and fill it with symbolic links to the matched messages, and the visit this special Maildir with Wanderlust. I'll include the code here to contrast it with the more elegant solution that we saw before, but also because the approach taken might be easily adapted for other mail-clients.

;; search using mutt
(defvar mu-wl-mu-program     "/usr/local/bin/mu")
(defvar mu-wl-search-folder  "search")

(defun mu-wl-search ()
  "search for messages with `mu', and jump to the results"
   (let* ((muexpr (read-string "Find messages matching: "))
          (sfldr  (concat elmo-maildir-folder-path "/"
                    mu-wl-search-folder))
          (cmdline (concat mu-wl-mu-program " find "
                      "--clearlinks --format=links --linksdir='" sfldr "' "
                     muexpr))    
          (rv (shell-command cmdline)))
    (cond
      ((= rv 0)  (message "Query succeeded"))
      ((= rv 2)  (message "No matches found"))
      (t (message "Error running query")))
  (= rv 0)))

(defun mu-wl-search-and-goto ()
  "search and jump to the folder with the results"
  (interactive)
  (when (mu-wl-search)
    (wl-summary-goto-folder-subr
      (concat "." mu-wl-search-folder)
      'force-update nil nil t)
    (wl-summary-sort-by-date)))

;; search by pressing 'Q'
(define-key wl-summary-mode-map (kbd "Q") ;; => query
  '(lambda()(interactive)(mu-wl-search-and-goto))) 
(define-key wl-folder-mode-map (kbd "Q") ;; => query
  '(lambda()(interactive)(mu-wl-search-and-goto)))

After installing mu and putting the above in your wanderlust startup file, you should be able to search by pressing Q. The mu documentation has an example for mutt as well.

conclusion

It's straightforward to integrate advanced searching capabilities to Wanderlust using mu, and thanks to Sam B., it's gotten a lot easier! The second (old) approach may be useful as 'inspiration' for use in other e-mail clients as well, if they do not provide the kind of hooks that the first solution needs.

IELM: a REPL for emacs

2011-03-26T14:18:00.000+02:00

Emacs-lisp (elisp) is a nice language to play around with code and try things as you develop them – explorative programming. I often use the *scratch* buffer for that, but sometimes it's nice to use a so-called 'REPL' ( Read-Eval-Print-Loop) instead. A REPL is a sort-of command-line interface where your expressions are evaluated as soon as they are considered 'complete' and you press Enter.

So, enter Emacs's built-in repl: IELM. You can activate it with M-x ielm, and the interaction looks something like the following:

*** Welcome to IELM ***  Type (describe-mode) for help.
ELISP> 123 
123
ELISP> (+ 1 2)
3
ELISP> ;; comment
ELISP> (defun fac (n)
         (if (= 0 n)
           1
           (* n (fac (- n 1)))))
fac
ELISP> (fac 5)
120
ELISP>

By default, IELM evaluates complete expressions automatically as soon you as you press Enter. So one thing to remember is that if you want to have multi-line expression (like above), you must make sure that after each line the expression is not complete (i.e., the brackets are not balanced) -- otherwise the expression will be evaluated too early. That makes modes like autopair or paredit a bit inconvenient for this.

If you don't like that behavior, you can do:

(setq ielm-dynamic-return nil)

which will allow you to Enter as much as you want and only evaluate things when you press C-j. But then you might as well use *scratch* I suppose. Personally, I use IELM mostly as a calculator.

executable source code blocks with org-babel

2011-02-27T14:32:00.003+02:00

org-babel is the mechanism that org-mode offers for evaluating (executing) blocks of source code embedded in your org-mode-documents. This is useful for so-called reproducible research, i.e., where you allow your readers to go through the steps that led to your results.

Here, I'm just scratching the surface with some simple examples.

source code blocks

Let's first look at how it all began: source code blocks. I guess most org-mode-users will be familiar with those: the ability to include syntax-highlighted ('font-locked') snippets of source code in org-documents. We discussed source blocks before, they look like this:

#+begin_src perl
sub my_func {
        print "Hello, world!\n";
}
#+end_src

And note that code blocks can be edited in their 'native mode' using C-c'= (or, =org-edit-src-code).

When code block like this are exported to, say, HTML, they'll look like the following fully highlighted snippet (assuming you're reading Emacs-fu in it's full-color version):

sub my_func {
        print "Hello, world!\n";
}

evaluating source code

org-babel takes this a few steps further: instead of just looking at source code, we can actually evaluate (execute) it, using the org-mode-based system called org-babel.

If you have a recent version of org-mode (7.x or later), add the following to your .emacs (or equivalent):

(org-babel-do-load-languages
 'org-babel-load-languages
  '( (perl . t)         
     (ruby . t)
     (sh . t)
     (python . t)
     (emacs-lisp . t)   
   ))

This enables org-babel for the mentioned languages; there are many other languages available as well.

Now, suppose we have a snippet of python in an org-mode-buffer:

#+begin_src python
def hello(str):
        return "Hello, " + str + "!"
return hello ("dude")
#+end_src

You can move the cursor (point) inside the src-block and press C-c C-c (or, org-confirm-babel-evaluate). This causes the block of code to be evaluated (executed), after asking you for confirmation. The result will inserted below the block, like:

#+results:
: Hello, dude!

Note, in the hello example, the result of the block is the value of the evaluation - that is, the value of the last expression evaluated. This is the also the default, so we don't need to (but could) write:

#+begin_src python :results value

The alternative is to use the (standard) output of the function, which is activated with :results output, e.g.:

#+begin_src sh :results output
   echo "Hello $USER! Today is `date`"
#+end_src

Moving to this block and pressing C-c C=c would get you something like the following – probably with a different username and time:

˜#+results:
: Hello djcb! Today is Sun Feb 27 13:51:50 EET 2011

almost like functions

org-babel also allows you to refer to the code blocks from elsewhere in your document, by labeling your code-blocks with srcname. Let's say we have some Ruby code to revert a string:

#+begin_src ruby
def revert(s)
  if s == "" then 
    return ""
  else
    return s[-1].chr + revert(s.slice(0, s.length()-1))
  end
end
revert(str)
#+end_src

We can now 'call' this block; note that we get the result of evaluating the block. So if you want to use the result of a function in the block, you also need to add the call to that function (see the last line).

Now, we can use:

#+call: revert(str="VeryCoolStuff")

And we get:

: ffutSlooCyreV

Note, due to some limitation/bug in my version of org-babel, the strings should not contain spaces or other special characters, so the following will give result in an error note:

˜#+call: revert(str="Very Cool Stuff")

Whenever you try to evaluate a code block, emacs will ask for confirmation -- this is important, because of the obvious security implications of executing unknown code. Anyway, if you do trust the code, you can use the following to skip the confirmation:

(setq org-confirm-babel-evaluate nil)

These simple examples do not really capture the power that org-babel brings, but it's a start. There is quite a bit of documentation for org-babel to help you further. Finally, if you are already using org-babel, feel free to share your experiences in the comments!

keeping your secrets secret

2011-02-10T22:42:00.002+02:00

If you want to keep your secrets secret, it is a good idea to encrypt your data; I usually do that for files with passwords for various services, banking data, and so on. Since version 23, Emacs includes a package called EasyPG (an interface to GnuPG) which makes this seamless – just make sure that you have GnuPG installed.

It's easy to use EasyPG – the only thing you need to do is adding the .gpg -extension to your files, and EasyPG will automatically encrypt/decrypt them when writing/reading. So, for example, to create an encrypted org-mode-file, simply visit (C-x C-f) a file with a name like myfile.org.gpg; emacs opens this in Org-Mode (just like any .org-file). When you want to save the file, emacs will ask you for a password, and with this same password, you can open it again. Don't forget that password!

account data

You can store any kind of secret data in your encrypted files. One type I find particularly useful is to store account data (user names, passwords) for various services there. For example, I use the emacs identi.ca-mode client, which gets its account data through variables identica-username and identica-password.

I do not want to put this information in my main .emacs file for safety reasons, but instead, put it an encrypted file, together with the account data for other services (mail, twitter etc.). Emacs' require does not understand encrypted files, but load-library does. To deal with that, I have two files, secrets.el and secrets.el.gpg (in my load-path):

;; secrets.el
(load-library "secrets.el.gpg")
(provide 'secrets)

and

;; secrets.el.gpg
(setq identica-username "djcb"
      identica-password "$ekr3t")
;; ... other passwords ...

Now, in my .emacs I have a function for various services, like:

(defun start-identica ()
  (interactive)
  (require 'secrets)
  (identica-friends-timeline))

This will prompt me for the password, but only if I use anything that requires the secret data, and only once per session.

Update: as Richard notes in the comments, you can also use require by explicitly specifying the filename (parameter two). That might actually be easier -- thanks Richard!

using public keys

By default, EasyPG performs symmetric encryption; if you want to use public key encryption instead (useful when you want to share the encrypted files with others), you can use:

;; 'silent to use symmetric encryption
;; nil to ask for users unless specified
;; t to always ask for a user
(setq epa-file-select-keys t)

The 'users' in this snippet are the people in your GnuPG-keyring – EasyPG lists your keyring inhabitants, allowing for easy selection. You can also specify the people who can decrypt your file by putting something like the following at the beginning of the file you want to encrypt.

# -*- epa-file-encrypt-to: ("foo@bar.org") -*-

so

EasyPG brings more functionality for encryption, decryption, signing, managing your keyring and so on, but I haven't used that much yet. Anyhow, the automatic support for reading/writing file is really nice.

extending ERC with your own commands

2011-02-02T20:40:00.000+02:00

ERC is the leading Emacs-based IRC-client; I already discussed ERC before. I have been using ERC a lot in recent times, as it's an essential way to communicate at work with team members in remote locations. There are other IRC-clients – most people around me seem to use either irssi or xchat, but these don't integrate so well with my emacs-based workflow, the easy with which it can be extended to do exactly what I want; in this although they have their own strenghts. One of the great strengths of ERC is article I give some examples.

Apart from chatting, you can send commands (long list) to the IRC-server, for example to request information about other users, change your 'nick', leave the channel, and so on. As in most IRC-clients, you can send these commands with ERC by prefixing them with /, so you'd type:

/nick ninjaturtle

to change your nickname.

The nice thing about ERC is how easy it to add your own commands to this. In your .emacs (after loading ERC), you can add something like:

(defun erc-cmd-MYSYSTEM ()
  "show some information about my system"
  (let ((str (shell-command-to-string "uname -a")))
    (when str (erc-send-message str))))

Or, add add a function called erc-cmd-XXXX (with the XXXX being the command name in capitals, will add command XXXX, which you can invoke with /XXXX or /xxxx). So, with the above function, I can now do something like:

ERC> /mysystem
<djcb> Linux cthulhu 2.6.35-25-generic #44 SMP Fri Jan 21 17:40:48 UTC
       2011 i686 GNU/Linux

Let's look at some other (somewhat) useful command: /calc; again, just a small example, I'm sure something can come up with something a bit more elegant - perhaps using emacs' built-in calc.

(defun erc-cmd-CALC (&rest args)
  "calculate value of some expression using bc"
  (let ((expr (mapconcat 'identity args " ")))
    (when (length expr)
      (let ((result (shell-command-to-string (concat "echo '" expr "' | bc "))))
        (when result (erc-send-message (concat expr " = " result)))))))

ERC> /calc 2 * (3 + 4) / 7
<djcb> 2 * (3 + 4) / 7  = 2

Now, a small warning, just because it's easy to dump the output of, say, cowsay in an IRC-channel using your own /cowsay command, does not mean it is a good idea – in fact, using something like that is guaranteed to get you kicked out fairly quickly from many channels.

That being said, I'm sure many people have come up with much more clever things than the examples here; feel free to share your inventions in the comments!

setting the frame title

2011-01-06T17:47:00.002+02:00

The 'frame title' (window title) that emacs uses in graphical environments defaults to something like emacs@hostname.

Of course emacs lets us customize this, by changing the value of frame-title-format. Emacs accepts many different things there, (see the documentation for frame-title-format and mode-line-format for that), but let's look at an example.

Instead of the default emacs@hostname, I find it more useful to include the name of the file I'm working on instead, or, in case of non-file buffers, the buffer name. To do this, I have something like the following in my .emacs:

(setq frame-title-format
  '("" invocation-name ": "(:eval (if (buffer-file-name)
                (abbreviate-file-name (buffer-file-name))
                  "%b"))))

As you see, frame-title-format is a template for the items that are present in the title bar; i.e.. emacs concatenates the items in the list, and it supports various %-constructs, which are replaced with actual values; see below.

In addition to the %-constructs, you can use :eval to make emacs evaluate the expression whenever it wants to update the title bar.

invocation-name is the name of the emacs binary.

abbreviate-file-name replaces the home directory part in file names with ~; for very deep paths it might be nice to do some abbreviation as well as some shells do; this is left as an exercise to the reader :)

You can experiment with some other things to put in frame-title-format; use the :eval construct as above to use emacs-lisp functions, and the various %-specifiers which are replaced by certain values; the emacs documentation lists the following:

%b -- print buffer name.      %f -- print visited file name.
%F -- print frame name.
%* -- print %, * or hyphen.   %+ -- print *, % or hyphen.
      %& is like %*, but ignore read-only-ness.
      % means buffer is read-only and * means it is modified.
      For a modified read-only buffer, %* gives % and %+ gives *.
%s -- print process status.
%i -- print the size of the buffer.
%I -- like %i, but use k, M, G, etc., to abbreviate.
%p -- print percent of buffer above top of window, or Top, Bot or All.
%P -- print percent of buffer above bottom of window, perhaps plus Top,
      or print Bottom or All.
%n -- print Narrow if appropriate.
%t -- visited file is text or binary (if OS supports this distinction).
%z -- print mnemonics of keyboard, terminal, and buffer coding systems.
%Z -- like %z, but including the end-of-line format.
%e -- print error message about full memory.
%@ -- print @ or hyphen.  @ means that default-directory is on a
      remote machine.
%[ -- print one [ for each recursive editing level.  %] similar.
%% -- print %.   %- -- print infinitely many dashes.
Decimal digits after the % specify field width to which to pad.

So, if we'd like to include the host (system) name and some indication of the status of this buffer, we could do something like:

(setq frame-title-format
  '("emacs%@" (:eval (system-name)) ": " (:eval (if (buffer-file-name)
                (abbreviate-file-name (buffer-file-name))
                  "%b")) " [%*]"))

Of course, some of the information is available elsewhere already, but it might be clearer in the frame-title. Or not – there's a lot of room for tweaking and experimentation here.

color theming with emacs 24

2010-12-30T17:18:00.000+02:00

The emacs development team is hard at work on emacs 24. As far as I know, there is no planned date for it yet. I'll write more about all the new cool things when we're a bit closer to the release date, but I'd like to highlight emacs 24 color-theming already, as it's an area people outside the core development theme should be able to contribute to as well.

Here at Emacs-fu, we already discussed color-theming and in particular the zenburn color theme; this was all based on the color-theme-package. While being popular, there were a few problems with that package, which is why emacs-24 comes with a new scheme for doing this.

The current development versions of emacs ship with a few themes (tango, tango-dark and wheatgrass), which you can activate with M-x load-theme. It would be great to include some more color themes, and to encourage this, emacs maintainer Chong Yidong has written the GNU Emacs Theme Generator (currently in bèta), which helps you in the process of making a simple theme. This tool currently only support changing colors, and not e.g. the boldness or slant, but it's a nice way to get started, and to immediately see the results.

For more complex theming, there is M-x customize-create-theme; however, that is built on the (in my opinion) cumbersome customize-interface, so I'll probably start by creating a basic theme with the web tool, and then edit it by hand. If you design some attractive color theme and would like to propose it for inclusion in emacs 24, you can send it to emacs-devel.

conkeror: web browsing the emacs way

2010-12-01T00:20:00.003+02:00

Web browsing is one of the few computer-based activities for which I usually do not use emacs. Of course, there are of emacs-based browsers like w3m, which is pretty good. But for the 21st-century web, a text-mode browser is a bit limited. There are some efforts underway to integrate a graphical web browser experience in emacs (e.g., using Xembed), but it will take a while before that is ready.
The next best thing to web browsing with emacs, is a browser that is inspired by emacs. Such a browser exists: it's called conkeror (not to be confused with KDE's Konqueror). conkeror is a Mozilla-based browser that brings an emacs-like experience to web browsing. I've been using it for more than a year now as my primary browser, and I am quite happy with it.
Conkeror is a user-interface for the normal Mozilla/Firefox engine (xulrunner); this means that all those websites that work with Firefox, work just as well in conkeror, including things like ad-blockers, Java, Flash etc. and many plug-ins. This is a very important point for me.
If you like emacs, you'll probably also like conkeror. For starters, it uses many of the same key bindings – C-x C-f will open a url in a new buffer (tab), C-x 5 2 will open a new window (frame), I can inspect a key-binding with C-h k… and so on. Some of the single-key shortcuts are the same as those in w3m, like g to go to a webpage, or B to go back. Conkeror is fully keyboard-driven; it allows you do almost anything on the web without using the mouse – it can overlay numbers on items in a webpage so you can interact with them by their number. Of course, you can still use a mouse if you want, too.
The conkeror wiki gives many more examples. It also discusses installation in quite some detail, which makes life a bit easier for me :) Instead, I will just list a couple of the customizations I have made and encourage you to try for yourself.

configuration

Like emacs, conkeror is very configurable. The big difference is that conkeror uses Javascript instead of Elisp for the configuration; however, the concepts and naming should be familiar for emacs-users. Conkeror's equivalent of ~/.emacs is ~/.conkerorrc. Below are some snippets from my setup, that can hopefully help you to create your Perfect Browser ™; all examples below are based on the latest development version of Conkeror, as per end of November 2010.
First, some basics:

//allow for 'contrib' stuff
load_paths.unshift("chrome://conkeror-contrib/content/");

// teach me something whenever I start my browser
homepage = "http://en.wikipedia.org/wiki/Special:Random";

// give me new tabs; open buffers (tabs) in the background
require("new-tabs.js");
require("clicks-in-new-buffer.js");
clicks_in_new_buffer_target = OPEN_NEW_BUFFER_BACKGROUND; 
clicks_in_new_buffer_button = 1; //  midclick links in new buffers with

// auto completion in the minibuffer
minibuffer_auto_complete_default = true;
url_completion_use_history = true; // should work since bf05c87405
url_completion_use_bookmarks = true;

modeline customization

As in emacs, you can customize the modeline. Also in good emacs tradition, this is far from intuitive…

require("mode-line.js");
// funky icons in the modeline
require("mode-line-buttons.js");
mode_line_add_buttons(standard_mode_line_buttons, true);

// we'd like to see the # of buffers being loaded 
add_hook("mode_line_hook", mode_line_adder(loading_count_widget), true);
// we don't need a clock
remove_hook("mode_line_hook", mode_line_adder(clock_widget));

bookmarks

Plain-old bookmarks are easy to add with define_webjump – and you can just bind them to a short string. You can then 'jump' to the corresponding website by pressing g and then this short string. For example, to go to Emacs-Fu, you could type g efu RET. No mousing around needed.

// some bookmarks
define_webjump("conk",  "http://conkeror.org");
define_webjump("efu",   "http://emacs-fu.blogspot.com");
define_webjump("lkml",  "http://lkml.org");
define_webjump("ew",    "http://emacswiki.org");
// ...

smart links

Smartlinks are just like normal bookmarks, which the one difference that they contain an %s-parameter which will be replaced by whatever you type after the name of the bookmark. Thus, g imdb grande bouffe RET would take you to the IMDB-page about the movie La Grande Bouffe.
Some examples:

define_webjump("so",    "http://stackoverflow.com/search?q=%s");
define_webjump("yts",   "http://www.youtube.com/results?search_query=%s&aq=f");
define_webjump("imbd",  "http://www.imdb.com/find?s=all&q=%s");
// ...

integration with emacs

Another useful feature in conkeror is the ability to interact with Emacs (or any other text editor), so you can use emacs for writing text in web pages; for example, when you're using emacs-daemon (you should), you could can add the below, and C-i will then take you to emacs whenever you are in a text field in a web page.

editor_shell_command = "emacsclient -c";

adding your own functions

It's fairly easy to add your own functions; admittedly, I'm still at the beginning stages with that, but it's not too hard to combine the internal function, and assign them to key bindings. Some examples:

// copy url with C-c u
interactive("copy-url",
        "Copy the current buffer's URL to the clipboard",
        function(I) {
            var text = I.window.buffers.current.document.location.href;
            writeToClipboard(text);
            I.window.minibuffer.message("copied: " + text);
        }
);
define_key(default_global_keymap, "C-c u", "copy-url");


// reload conkerorrc with C-c r
interactive("reload-config", "reload conkerorrc",
       function(I) {
          load_rc();
          I.window.minibuffer.message("config reloaded");
       }
);
define_key(default_global_keymap, "C-c r", "reload-config");

It's not necessarily so easy to find the exact functions / objects you need to accomplish what you want. There's a certain learning curve – just like when using emacs.

integration with org-mode

The integration with emacs can go further than merely editing text fields though; it's possible to integrate conkeror with org-mode in emacs; I have the following in my .conkerorrc (this requires emacs-daemon), based on the code in WOrg:

// org-protocol stuff
function org_capture (url, title, selection, window) {
    var cmd_str =
        'emacsclient \"org-protocol:/capture:/w/'+url+'/'+title+'/'+selection+'\"';
    if (window != null) {
      window.minibuffer.message('Issuing ' + cmd_str);
    }
    shell_command_blind(cmd_str);
}

interactive("org-capture", "Clip url, title, and selection to capture via org-protocol",
          function (I) {
              org_capture(encodeURIComponent(I.buffer.display_uri_string),
                        encodeURIComponent(I.buffer.document.title),
                                encodeURIComponent(I.buffer.top_frame.getSelection()),
                        I.window);
          });
// capture with C-c c
define_key(content_buffer_normal_keymap, "C-c c", "org-capture");

Then, on the emacs-side (in your .emacs), you should have a capture template for this; for example:

;; ;; the 'w' corresponds with the 'w' used before as in:
;;   emacsclient \"org-protocol:/capture:/w/  [...]
(setq org-capture-templates
  '(
     ("w" "" entry ;; 'w' for 'org-protocol'
       (file+headline "www.org" "Notes")
       "* %^{Title}\n\n  Source: %u, %c\n\n  %i")
     ;; other templates
))

Now, when in conkeror, you can select some text, push C-c c ('capture'); emacs will offer you to save this text, including a link to the source, the date and so on, and saves it for later retrieval. I really love this feature!

so…

These were just a couple of the many things you can do with conkeror; there's so much potential here. I haven't discussed many of the other powerful features, such as the page-specific modes, that give special features to specific websites, be it GMail or Wikipedia.
I've been using this fine browser for a year or so now, and I really like it. There are a few rough edges here and there, but it's quite amazing what the small development team has accomplished. I heartily recommend it – for web-browsing the emacs-way, there's simple no better alternative.
Finally, if you're using conkeror already, and have some clever tricks you'd like to share, feel free to do so in the comments.

undo

2010-11-15T22:33:00.005+02:00

One of the advantages that text-editors have over daily life is the ease of undoing things. Emacs in particular has a powerful undo-system to return to the previous state of things.

Undo can be activated by pressing C-x u or C-_; if you are more comfortable with using C-z for undo (as is the standard in many non-Emacs environments), you can of course add that key binding as well, by putting in your .emacs:

(global-set-key (kbd "C-z") 'undo)

This overrides the default of C-z triggering suspend-frame, which is not a great loss for most people.

Emacs-undo has some nice features - for example, if you have selected some text ('marked a region'), the undo operation only applies to that area. At the same time, however, the undo-model can be confusing: in emacs, undo is treated like any other command, which means that undo can be applied even to… undo, which is different from what most other editors do. Let me give an example – if it's confusing or tedious then, well, that's what it is…

Suppose I type

hello
world

now I press C-_, and I get

hello

Now I type foo

hello
foo

And press C-_ C-_; and I get back:

hello
world

This is because we're 'undoing the undo' of adding the word 'world', and thus, it reappears! When you try this in most other editors, it would result in

hello

because those editors completely forget about 'world' after it is undone.

So, emacs' model is strictly more powerful - but some (many? )people find it a bit confusing, esp. when a series of 'undos' is interrupted by a 'do'.

If you prefer the model that many other editors use, you might be interested in redo-mode, in particular in RedoPlus. Using that package, undo (or rather, redo) follows a different model. In that model, redo is 'special': it's not registered as a buffer change, and as such it's conceptually different from the redo=undo-undo model that emacs uses by default. As seen above, you actually lose some information in the process.

Yet another way to tackle the undo-problem is implemented by UndoTree: the states of your buffer are seen as nodes in a tree, and you can freely move to specific nodes. UndoTree is as powerful as the emacs system, yet easier to understand. It can even visualize the tree of changes - and you can then by clicking on a node go back to the corresponding buffer state.

Now, when using UndoTree, let's look at our example again:

We started with:

hello
world

then did C-_ (which removed 'world') and typed 'foo' to get:

hello
foo

Now press C-u again, and 'foo' disappear. Now we press C-x u (undo-tree-visualize) and we get a buffer with:

  |
  o
  |
  |
  x
  | 
 / \
o   o

and we can now visually move to any of the nodes, and our buffer is instantly brought back. Cool! The two branches correspond to the states 'world' and 'foo'. I have been undo-tree-mode for the last few weeks, and it works very well: usually I don't even notice it, but when I need the extra power, it's there.

I am told that UndoTree is inspired by the way the vim-text editor does this. Anyway, there is another very powerful feature in the vim undo-system that would be nice to have in emacs to: time-based undo. In vim you can e.g. say something like:

:earlier 5m

to go to the state of your buffer 5 minutes ago. That would be a nice addition for undo-tree-mode!

Update Tavis Rudd notes that pressing t in undo-tree-visualizer-mode (i.e.. what you see when your press C-x u) will give you timestamps instead of o and x:

                  |
                  | 
             18:54:20
                  |
                  |
             18:54:20
          ________|___ 
         /            \
     18:54:15       18:53:37
        |              |
        |              |
     18:54:15       18:53:37
     ___|___           |
    /       \          |
18:54:10  18:53:43  18:53:36

auto-complete-mode

2010-10-23T15:59:00.006+03:00

Recently, we discussed CEDET in the interview with Eric Ludlam. CEDET has a deep understanding of the source code, and assists the development process by exploiting that knowledge. For example by drawing class diagrams (COGRE) or providing auto-completion for function names and parameters.

Currently, however, CEDET is also be a bit hard to set up effectively, and may also not support your programming language yet. Therefore, it's still useful to look at some other packages that can substitute (part of) the functionality.

For me, auto-complete-mode has been very useful for that. It's not as fancy as CEDET in the sense that it does not really understand the code – but in practice I found it to work quite well for both C/C++, Elisp and shell scripts. It can even display the docstrings of functions. And when editing shell-scripts, it can complete path names as you are editing the scripts; very nice.

To install, follow the instructions. Then, in your .emacs, have something like:

(when (require 'auto-complete-config nil 'noerror) ;; don't break if not installed 
(add-to-list 'ac-dictionary-directories "~/.emacs.d/ac-dict")
  (setq ac-comphist-file  "~/.emacs.d/ac-comphist.dat")
  (ac-config-default))

After that, M-x auto-complete-mode to start using it. Alternatively, there's a YouTube-video explaining how to install and use auto-complete-mode; recommended. In any case, it is fully documented.

auto-complete-mode uses a configurable set of sources from which it takes it knowledge about what can be completed. For example, when writing in org-mode, it takes its input from

(ac-source-filename ac-source-abbrev ac-source-dictionary
 ac-source-words-in-same-mode-buffers)

while in a c-mode buffer it is (in my case):

(ac-source-filename ac-source-yasnippet ac-source-gtags ac-source-abbrev
ac-source-dictionary ac-source-words-in-same-mode-buffers)

You can customize this, and (for the more ambitious), it's possible to add your own sources as well.

interview with Eric Ludlam (CEDET)

2010-09-27T07:42:00.000+03:00

One of the notable new features of emacs 23.2 was the inclusion of CEDET. CEDET adds IDE-type functionality to emacs, and one only needs to read the responses to the 100th post to see the great interest in that.

The man behind CEDET is Eric Ludlam (EML), a long-time Emacs user and developer. He kindly answered the many questions we had for him. Thanks, Eric!

djcb: Eric, could you tell us a little bit about yourself? And about that fantastic hobby of yours, building siege engines?

EML: I manage a software engineering team at the MathWorks. The MathWorks are the creators of Matlab. In my spare time I maintain CEDET, the Matlab support for Emacs, and build replicas of ancient siege engines.

I've been building catapults of various types for use at the World Championship Punkin' Chunk since 1998. My team started with a traction trebuchet, then a HCW Trebuchet, then moved to Human Powered Centripetal, and finally to the torsion division with MistaBallista. As far as I know, Mista Ballista is the worlds largest farthest throwing currently functional ballista.

Most recently, I got to help demolish a building where I work by shooting stuff at it, which was a lot of fun.

djcb: How did you get involved with Emacs? Do you spend a lot of time with it?

EML: I've been hacking Emacs since version 18.54 on Ultrix because the alternative was vi. My first post (and thus contribution to Emacs) was to gnu.emacs.sources on June 6, 1992. I've used Emacs to work on C/C++ code for many years which inspired all the various parts of CEDET, but these days I don't get much coding time.

My work with Emacs and CEDET is seasonal currently. The summers are usually busy with family activities, and my falls are busy getting the catapult ready, so CEDET work usually happens in the winter.

djcb: Can you tell us a bit about the background of CEDET?

EML: I started with some really basic editors and eventually with LSE (Language Sensitive Editor) on VMS. LSE was pretty cool. When I switched OSes to Ultrix and was forced to use Emacs, and discovered you could script it, I was hooked. My first big Emacs hack was etalk, an implementation of Unix talk in Emacs.

In one of the Emacs related newsgroups, a spoof story floated around about how Emacs became sentient, and started writing code for Richard [Stallman] instead of the other way around. Since then I've always wanted to get Emacs to start writing my code for me. I wrote cparse.el, a regexp nightmare that could parse almost any C file into a sequence of highly detailed tags. The tags could be used to then generate code, and I had a cool comment writing utility, automatic prototype generation, and some navigation features. On the whole it failed for many reasons.

The concept, however, continued. CParse became the basic idea behind what is now the Semantic package in CEDET, though none of the old stuff remains beyond some echos in some SRecode utilities.

My end goal is to provide round-trip code management in Emacs. Emacs needs to be able to read your code, allow you to perform transformations in the code in an abstract way, and then write new code for you. Everything in CEDET is building toward that goal. It is taking a long time, and you can see it starting to take shape. Semantic can parse the code, COGRE can manipulate UML diagrams representing your code, and you can export diagrams into code through SRecode. Unfortunately this isn't a round-trip solution as the generated code currently should not replace existing hand-written code.

Can you tell us a bit about the CEDET-project?

EML: I maintain CEDET and field questions on the mailing list. There are several contributors who either own some tool in the "contrib" area, fix bugs, answer questions or apply patches for new features. There has always been someone to pick up the slack when I'm busy elsewhere, and I've greatly appreciated that.

The easiest (and most common) way to contribute code to CEDET is to provide support for some new language, or to create a language agnostic tool using the CEDET APIs. As with Emacs, you need to be able to assign copyright to the FSF to contribute to CEDET's core, but new language support or utilities can have a home in the contrib area as well.

djcb: CEDET is part of Emacs since 23.2. Can you tell us a bit about how that happened?

EML: I've been providing assignments for the parts of CEDET since 1996 or so. For Emacs 23.1, CEDET was at a stable and useful enough state that Chong Yidong was willing to do the work to integrate it into Emacs. My ability to get a legal release for CEDET in time for Emacs 23.1 failed, so it went into 23.2 instead. It is my understanding that CEDET's smart completion engine reached a performance and reliability point that made it desirable to have in Emacs.

Emacs currently includes the parts of CEDET needed to make EDE, the project management system, Semantic and it's user tools, and SRecode all work from a user perspective. Emacs lacks the Semantic development environment, needed for writing new language support, and COGRE, the UML diagram editing tool.

djcb: Are there plans to include those parts as well?

Yes. It is important for users with a stock Emacs to develop new languages using the missing Semantic development tools. I don't know if COGRE will ever go in, though I expect that this will be done via the new package management system [elpa].

djcb: Did you ever try IDEs such as Eclipse? How do you think CEDET stacks up against such programs?

EML: I have used Visual Studio more than Eclipse, and certainly watched demos on how these and other tools work.

These tools win over CEDET's features in that they usually integrate directly with the compiler, VM or whatever, and have very good completion engines and UIs that you can interact with.

CEDET wins in that you don't need a compiler, or even code that can compile for it to work and start providing useful completions. It can infer an awful lot from a project.

CEDET's language support structure is thus simple in comparison, and CEDET supports many more languages as a side effect. It also wins because it is in Emacs, and I've done my best to try and match the "Emacs Way". For an Emacs user, this is intuitive, but can appear quirky to outsiders.

djcb: What about other development tools for in emacs?

EML: There are a lot of language specific solutions like GCCSense, slime, JDEE, and others out there. These projects are great in that they take a language, and push it to the edge of what you can do, and the users generally love that stuff. When someone wants to do the same thing, like when CSDE started for C#, and it tried to copy JDEE, it was just that, a copy that didn't quite make it.

It is my hope that CEDET will become the target of choice for users who want to make their language support in Emacs the best. They will save a lot of time doing so as well. The same infrastructure for integrating in external tools can be used to get improved results out of CEDET, but CEDET will handle converting that into a representation that would then allow any tool built on CEDET to work. This is the same model that worked well for comint.el, and gud.el.

Yasnippet is a bit different in the way it "competes" with SRecode. My first implementation of SRecode tried recycling tempo templates, but I couldn't get it to work. In fact all the template systems I investigated fell short of what I was trying to do, so I had to roll my own, and ended up using a variant of the Google template format.

The key difference is that the goal was for SRecode to provide a series of base templates for code generation. A tool writer would then write some tool to generate code. A user would then use the tool, and say "This is great, how do I change where the { goes?"

The answer is to override the template with that detail in it without interfering with the system templates. That only works if the templates are sufficiently granular that the changed template can be simple. Template reuse needs to be high so that if your company formats your methods as:

int mymethod() { implementme() };

instead of

int mymethod() {
}

that one template change will allow this to happen for all code generated from every tool.

Thus, the audience for yasnippet and SRecode is quite different. Of course you could do yasnippet like things with SRecode if someone took the time to improve the field-editing feature in SRecode, but that has not been my focus.

djcb: Do you follow the overall Emacs development process? Are there things you would like to see changed/improved?

EML: I watch the emacs-devel mailing list, mainly to see if anything related to CEDET goes by that I can help with, or what the latest cool feature might be. My first contribution of Speedbar to Emacs in Emacs 20 helped drive some features related to overlines, boxes, and other face attributes that appeared in Emacs 21.

In the future, once CEDET and Emacs cross merge techniques are hashed out, I would expect some key parts that need performance improvements might move into C. Another part of CEDET that I'd love to see become bound closer to Emacs is mode-local.el. It tries to simulate mode-local variables and mode-local functions. This is critical in a complex system like CEDET that needs to provide a language support author with fine grained control. There are good reasons not to make what is currently implemented "the Emacs way", but it would be nice to resolve those and enable mode authors a with a more powerful way to customize the user experience.

djcb: Do you have specific plans for CEDET in the future?

EML: Here is the short list:

Improve Emacs/CEDET cross merging
Offload tag storage to an external process - needed for scalability
Design/define a "CEDET mode" as a way of simplifying the confusing array of distinct tools and modes that make up CEDET now.
Finish the smart-context menu project
Resolve the "code replacement" problem of parsing a block of code, transforming it, and re-creating that code in place reliably.

djcb: In addition to all these 'generic' improvements, are there specific areas where new contributors could make a difference?

EML: Supporting new "stuff" in CEDET is one big win. Stuff can be:

New project types under EDE to ease transition from something like Visual Studio to Emacs.
Language support, such as parsers, or mode overrides. Finding ways to take existing cool tools, like JDE's beanshell, or slime's inferior lisp process and allowing it to do work for CEDET is another big win.
Templates for code generation in new languages.

Tool writing would also be good. JDEE's author Paul Kinnucan converted many bits of JDEE to CEDET and co-designed many of CEDET's parts along the way, such as semanticdb, and that was a huge help. ECB's current maintainer Klaus has also had a big impact on the way concepts are abstracted to a tool that depends on CEDET.

Naturally, joining the mailing list and fixing reported bugs and improving the doc is also a huge help, but not as exciting as writing new code. :)

djcb: Finally, many people want to start using CEDET, but it seems they have a bit of trouble to get started. Do you have any recommendations for them?

EML: Start with the cedet.info file which has many of the common setup configurations in it. If you run into something not explained well or at all, be sure to join the mailing list and be specific about how that doc failed. Very few questions on the mailing list refer to the doc, so the doc is rarely improved in a way that can help others.

Another good starting point is Alex Ott's article A Gentle Introduction to CEDET, which is very helpful.

Thanks a lot for your time, Eric! Wishing you a lot of success with CEDET and all your other projects!

narrowing buffer contents

2010-08-22T14:10:00.001+03:00

'Narrowing' is yet another of those many useful emacs features that took me years to appreciate, mostly because I never really tried it. I may not be the only one, so here's a short introduction.

Narrowing is the concept of hiding the buffer contents except for what you are currently working on. This is useful when you don't want to be distracted, but also because it allows you to execute commands only on the narrowed part. You can narrow different things:


what's shown	name	binding
region (selection)	`narrow-to-region`	`C-x n n`
current page	`narrow-to-page`	`C-x n p`
function	`narrow-to-defun`	`C-x n d`
everything	`widen`	`C-x n w`

I never used narrowing for the current page, but apparently it's used by e.g. Info-Mode to show only one page.

That last one is pretty important to remember; it's not totally obvious how to get back to 'normal' mode where you can see everything. For this very reason ('where the #>*$@ did my text go'), always-helpful emacs by defaults disables narrow-to-region (but, for some reason, not the other ones). To enable it, put the following in your .emacs:

(put 'narrow-to-region 'disabled nil)

Also note that the mode-line will show 'Narrow' when you're in narrow mode, lest you forget.

When you're using org-mode there is an additional one you might want to memorize:


what's shown	name	binding
subtree	`org-narrow-to-subtree`	`C-x n s`

I'm using that last one quite often; I have org-files where I keep meeting notes etc., and when in a certain meeting, I only want to see the notes for that specific meeting.

One bug? feature? of narrowing is that line-numbering is relative to the narrowed area rather than the full buffer. I'd prefer to have the real line numbers.

some handy key bindings

2010-07-30T21:23:00.002+03:00

Emacs offers many handy key bindings; every now and then I come across a new one, which has been hiding there somewhere for a decade or more… Here are some of my favorites – I'm listing those that are (a) often useful, (b) might not be known by everyone already (c) don't require any external packages or setup.

M-27 x gives you xxxxxxxxxxxxxxxxxxxxxxxxxxx; and, believe it or not, works also with different characters and numbers;
M-m jumps to the first non-whitespace character on the current line;
M-^ joins two lines into one – like vi(m)'s :join, except that point must be on the second line, not the first;
M-/ auto-completes based on words in all your buffers; there are more powerful alternatives, but this one does not require any setup;
C-h k followed by some key or key combination tells you what it does, C-h m describes the currently active modes, with their key bindings;
C-h f documents the current function, C-h v does the same for variables. C-h a gives you information about commands - for example to get date-related commands, press C-h a date. This will, however, also get you commands related to update; instead, you can use C-h a \bdate (because C-h a accepts regular expressions);
C-x C-o will delete all the empty lines around your current cursor position, except for one;
M-q re-aligns the current paragraph; I use it all the time when writing e-mails etc. (you might want to check out filladapt for a version that gives you a bit more smartness with indentations, lists etc.);
C-x 8 RET in a recent emacs version gives you an auto-completable list of special characters to insert. So if I need, say, the Yen-character, I type C-x 8 RET ye TAB and I get YEN SIGN, which RET will then insert: ¥. Note that the completion only works on the start of the character name, so if you'd want to include the α-character, you'd need to know that its UCS-name is GREEK SMALL LETTER ALPHA… (you can try *alpha or TAB the empty string, and search in the results buffer, but that's rather slow);
C-h l shows your last 300 key presses ('lossage'). Interesting to see, and it might be useful when defining keyboard macros.

What are your favorites? Please share them in the comments.

navigating through files and buffers with the lusty explorer

2010-07-21T17:29:00.000+03:00

I think quite a few people are using ido-mode to navigate through files an and buffers; we discussed it here already a long time ago. I am a happy ido-user myself – it took me some time to fully get full accustomed to the key bindings, but now it feels very natural. Definitely an improvement of my emacs user experience.

However, I am always looking for new things – and one of those is a sort-of ido-mode substitute. It's called the Lusty Explorer and it's the emacs implementation of an existing vim-plugin. It's quite similar to ido-mode; the difference is mainly that it shows all the files or buffers at the same time, in the way that shells (say, bash or zsh) do auto-completion.

The best way to show how it works is using an screencast (note, this is of a slightly older version). Lusty Explorer uses fuzzy matching; that means that I can type /etc/fo, and all items in /etc/ with names f.*o match.

To install lusty-explorer, simply copy lusty-explorer.el to your load-path, and put something like the following in your .emacs:0

(when (require 'lusty-explorer nil 'noerror)

  ;; overrride the normal file-opening, buffer switching
  (global-set-key (kbd "C-x C-f") 'lusty-file-explorer)
  (global-set-key (kbd "C-x b")   'lusty-buffer-explorer))

Side-note, the (when (require 'lusty-explorer nil 'noerror) ...) is there just make sure that no error is raised when lusty-explorer is not found, and the rest is ignored in that case. I use this construct for all packages that are not necessarily available everywhere I use my .emacs; thus, they will simply be ignored and not cause startup errors.

I've been using Lusty Explorer for about a week now, and I am quite happy with it. I still need some time (and maybe some more customization) to get used to the way it works - for example, I found the way ido-mode handles backspace a bit smarter. Also, ido-mode can be customized to a much greater extent. That might merely be a factor of the relative age of the packages – and I haven't really felt the need to customize Lusty Explorer too much. For now, I think I'm going to keep on using it. It's worth a try at least!

keyboard macros

2010-07-16T20:34:00.005+03:00

Keyboard macros are a truly classic emacs feature. Still, I only started to use them years after I got sucked into emacs – not so uncommon for emacs features… There may be more people like me, so let's raise the awareness a bit.

Keyboard macros allow you to record a number of keystrokes, and replay those at some later point. This can be a great time-saver when you need to do repetitive things. In many cases, they are an easy alternative to writing some elisp to get a job done. Note, keyboard macros are should not be confused with elisp-macros, which are something else altogether.

an example

So, when would we want to use a keyboard macro? Let's take some tedious task -- for example, we have a list of a few hundred names:

Newton, Isaac
Einstein, Albert
Maxwell, James
Turing, Alan
...

and we want to turn that into:

Isaac Newton
James Maxwell
Alan Turing
...

so, roughly, put the last name after the first name, and remove the comma.

We can solve this in different ways; we could simple change each line by hand. That's a fine solution if there are only a few lines, but it gets boring rather quickly.

Another way is to use regular expressions (see Building regular expressions); in this case, it's fairly easy to come up with one (assuming you know regular expressions). But let's see how we can solve it with a keyboard macro.

Schematically, we can solve this with the following:


action	key
go to beginning of a line	C-a
kill (cut) the first word	M-d
delete the next two characters	DEL DEL
go to the end of the line	C-e
insert a space	SPC
yank (paste)	C-y
go to the next line	C-n

This may look like some magical incantation, but it comes quite natural when you are actually doing the editing.

An important thing to remember when working with keyboard macros is that you do your commands in such a way that they can be repeated for each line. Suppose you would select Newton with shift-select, i.e., C-SPC at the beginning of the line and pressing the right arrow key 6 times – that works for Newton, but not for Einstein. Instead, we need to use M-d ('kill-word') instead.

defining a macro

Now that we have solved the problem for a single line, let's make a keyboard macro.

We move the cursor to the first line, and start the definition by pressing C-x (, or alternatively, F3. Then, we press the commands C-a, M-d, DEL DEL, C-e, SPC, C-y, C-n (as in the list above). To finish the definition, press C-x ), (or F4).

Hurray, we have our macro. Now, let's use it.

using the macro

Now, to execute the last defined macro, you press C-x e. We could repeat that for our whole list, but fortunately there's an easier way to repeat a macro n times, using a prefix argument. For example, to repeat the macro 123 times, you first press C-u 123 and then C-x e.

There's a slightly shorter way to do this: instead of C-u 123 we can write M-123, and for C-x e we can use F4 (kmacro=end-or-call-macro).

You can even repeat the macro until the end of the buffer is reached with C-u 0 C-x e; this only makes sense if the macros ever reaches the end of the buffer of course. (Remember that you can always terminate with C-g, keyboard-quit)

You can also apply your keyboard macro to all lines in the selected area (region) with M-x apply-macro-to-region-lines (or C-x C-k r). Important to remember: this will actually move the cursor (point) to the start of each line, and then execute the macro. If you want your macro like that, the go-to-the-next-line should not be part of your macro, or you will be skipping lines.

saving macros for later use

If you want to use multiple macros, you can name them. You can do this with M-x name-last-kbd-macro. If you name your macro, say, foo (inventive as we are), you can then execute it after that as M-x foo, which will be available until you exit emacs.

If you want to have the macro for future emacs sessions as well, you can use insert-kbd-macro, which will give you an elisp version of your macro. For our example, this will look like:

(fset 'foo 
   [?\C-a ?\M-d delete delete ?\C-e ?  ?\C-y ?\C-n])

Not very readable, but we can put this in .emacs, and we can use it the next time we start emacs as well. We can also add a key binding for this, for example:

(global-set-key (kbd "C-c f") 'foo)

This will bind foo to C-c f.

final notes

Keyboard macros can be useful and easy, but they are fundamentally connected to key presses – so, if you remap your keys to something different, your macros may not work anymore. Also, the macros are pretty much write-only in the way we use them here. You can edit them in the macro editor though, with M-x edit-kbd-macro M-x foo; we'll then get something like:

;; Keyboard Macro Editor.  Press C-c C-c to finish; press C-x k RET to cancel.
;; Original keys: C-a M-d 2*<delete> C-e SPC C-y C-n

Command: foo
Key: none

Macro:

C-a                     ;; move-beginning-of-line
M-d                     ;; kill-word
2*<delete>              ;; delete-char
C-e                     ;; move-end-of-line
SPC                     ;; self-insert-command
C-y                     ;; yank
C-n                     ;; next-line

Keyboard macros can be quite a useful trick in your arsenal. And I have not even gone into more advanced tricks like macros with variations or the macro ring. Please refer to the section Keyboard macros in the emacs manual (C-h r) for all the details.

And, finally, don't let the text-based example limit your imagination – you can turn just about any repetitive sequence of tasks into a macro.

console apps in emacs with multi-term

2010-06-30T23:05:00.002+03:00

multi-term

updated Whenever it makes sense, I try to use emacs for my computer-based activities; surely, programs like The Gimp or a graphical web browser cannot yet be replace by emacs, but I'm making progress. I like the ways emacs gives me to automate and speed-up my tasks; I get some return-on-time-investment.

2010 or not, I still spend quite a bit of time on the console. So why not do that from within emacs? There different ways to run shells within emacs.

The simplest one is shell (i.e,, M-x shell), which starts a simple shell, which does not support which does not support 'graphical' console applications, such as mutt, mc, htop.

Then there are term and ansi-term (M-x ansi-term) that do support such applications, which ansi-term supporting colors as well (it seems to have become the default for term in recent emacs versions).

Another one is the nifty EShell (included with emacs), which is not just a (simple) terminal, but also a full shell environment, and has integration with other things in emacs. It's nice, but has some of the limitations that shell has - you cannot run 'graphical' applications; also, I don't really need a shell, as I am quite happy with zsh (zed shell) already, which is more powerful, and I prefer a shell that works both inside and outside emacs.

For all these reasons, I am using MultiTerm, which has 'graphical' support that ansi-term has, but adds a nice extra, namely support for multiple terminals within emacs. I'm not fully up to date with the exact difference in the terminal support between the two, but I haven't had any problems so far.

You can install multi-term (put it in your load-path), and add the following to your .emacs:

(autoload 'multi-term "multi-term" nil t)
(autoload 'multi-term-next "multi-term" nil t)

(setq multi-term-program "/bin/bash")   ;; use bash
;; (setq multi-term-program "/bin/zsh") ;; or use zsh...

;; only needed if you use autopair
(add-hook 'term-mode-hook
  #'(lambda () (setq autopair-dont-activate t)))


(global-set-key (kbd "C-c t") 'multi-term-next)
(global-set-key (kbd "C-c T") 'multi-term) ;; create a new one

With this, C-c t will jump through your multi-term buffers (create a new one if it doesn not exist yet), while C-c T unconditionally creates a new terminal.

automatic pairing of brackets and quotes

2010-06-17T22:24:00.001+03:00

Some text-editors, notably TextMate for MacOS, have a nice feature where inserting a opening ( will automatically insert the closing ), and put the cursor in between them (and does same for [], {}, and various quote-marks).

Not surprisingly, there are some implementations for emacs as well; the best one I have found so far is called autopair, which was written by João Távora. It usually does things just right. Do things 'just right' is essential for such a tool; even small annoyances can disturb your flow. Autopair tries to do whatever makes the most sense for a given mode (programming language etc.), but it can be tuned as well.

After installation, you can automatically activate it for all modes with (in your .emacs):

(require 'autopair)
(autopair-global-mode 1)

Now, evaluate this or restart emacs, and enjoy the autopairing-magic!

Except for autopairing, autopair also takes care of autocleaning; that is, if I press ( it turns that into () (the pairing part), and if I press Backspace then, it removes the whole () (the cleaning part). This makes things much less annoying if you type a pair by accident. Autopairing is the kind of thing that can get annoying quickly if it does not things exactly right – and autopair succeeds!

Another nice trick it offers is autowrapping – that is, I select a word, press ", and automatically it's turned into "word". To enable that, you need to add the following:

(setq autopair-autowrap t)

Note: you might want to see the notes below about delete-selection-mode and cua-mode.

Anyway, autopair with autowrap makes for a really smooth editing experience, I love it! There are two small issues for me though. First, when the cursor in front of some non-whitespace, I'd like autopairing not to happen, and second, somehow I can't seem to get "-autopairing to work in org-mode; of course, that could be my own fault. These things might be tunable; I haven't tried very hard yet.

delete-selection-mode

Important to mention here is that autopair is (by default) not fully compatible with delete-selection-mode. As you may know, that is the mode that causes emacs to replace the current selection with a character typed, similar to what most other programs do. I think many people have it enabled in their .emacs with something like:

(delete-selection-mode 1)

If you want to keep on using that together with autopair, add the following to your .emacs:

(put 'autopair-insert-opening 'delete-selection t)
(put 'autopair-skip-close-maybe 'delete-selection t)
(put 'autopair-insert-or-skip-quote 'delete-selection t)
(put 'autopair-extra-insert-opening 'delete-selection t)
(put 'autopair-extra-skip-close-maybe 'delete-selection t)
(put 'autopair-backspace 'delete-selection 'supersede)
(put 'autopair-newline 'delete-selection t)

But, not that that still won't give you the autowrap behavior mentioned above. For that, we can use cua-mode.

cua-mode

We discussed CUA-mode before, focusing on its nice rectangle-editing features. But CUA-mode can also be an alternative for delete-selection-mode, and it goes together more nicely with autopair; so, instead of delete-selection-mode and the put's, add the following to your .emacs:

(setq cua-enable-cua-keys nil)           ;; don't add C-x,C-c,C-v
(cua-mode t)                             ;; for rectangles, CUA is nice

See the linked CUA-mode article for the 'why' of that first line. With this change, autopair should be working smoothly, including autowrap.

further customization

As I have hinted at, autopair can be tuned for different modes, and can differentiate between it's behaviour in literal strings, code, comments etc. The default are usually sane, but if you're interested, have a look at the documentation, in particular autopair-extra-pairs and the More tricks-section in the documentation.

worldcup games in your org-mode agenda

2010-06-10T21:57:00.000+03:00

A significant part of the world population will be watching the Football World Cup in South-Africa this month. For people who use org-mode to organize their lives, find the schedule of all the games in this message I sent to the org-mode mailing list.

In order to have the games show up in your agenda, make sure the file is in your org-agenda-files. If needed, you could add it with something like in your org-mode settings:

(add-to-list 'org-agenda-files "~/org/fifa-worldcup-2010.org")

One small issue with the schedule is that it use the South-African times, and there is no automatic way to adjust times for the local time zone. As a work-around, Juan Pechiar provided the following function which makes it easy to update all org-timestamps in a file:

(defun uphours (n)
  "update all timestamps n hours"
  (interactive "nAdd hours: ")
  (save-excursion
    (goto-char (point-min))
    (while (re-search-forward "[[<]" nil t)
      (when (org-at-timestamp-p t)
        (org-timestamp-change n 'hour)
        ))))

Evaluate this function (in emacs, put your cursor after the last ")"), then press C-x C-e. After that, you can go to the file with the world cup schedule, and give an M-x uphours, provide the offset for your timezone, compare to South-African time (positive or negative).

100th post

2010-05-20T10:29:00.003+03:00

100

With that last post, emacs-fu reached the 100 posts milestone! Hurray! Thank you for all the support, it's been a great ride so far, and there's so much more to write about - if only there were 36 hours in a day.

Anyway, to celebrate, I'll be off for the coming weeks (Korea), and I'm not sure if I have much time to blog from there. So, let's take this opportunity for a small reader poll: what would you be interested to read about? More programming-related stuff, more org-mode, more about integration with other programs, more interviews, more …?

Please leave your ideas in the comments. I'd be interested to hear!

Update: I am back now; thanks for all the replies. It seems that many people are interested in CEDET. In fact, I am interested in it myself as well, but am not using it right now, so it will take a while. For the time being, Alex Ott's Gentle Introduction might be the best way to get started.

zenburn for org-mode-generated html

2010-05-20T10:15:00.003+03:00

If you read this blog directly, instead of through some aggregator or feed-reader, you can now see the code blocks rendered in the nice zenburn color theme that I discussed before. I'm really enjoying it, so I added some style sheet definitions, so org-mode #+BEGIN_SRC / #+END_SRC blocks look as such in the web page (and just like they look on my screen), for instance:

(defun fibo (n) 
     "calculate the Nth (N>=0) fibonacci number in a simple yet
  inefficient way"
    (cond
      ((= n 0) 0)
      ((= n 1) 1)
      (t (+ (fibo (- n 1)) (fibo (- n 2))))))

;; now, gimme a list of fibo numbers 0..20
(mapcar 'fibo (number-sequence 0 20))

Note, I discussed the use of such code blocks earlier; it's one of many nice features of org-mode. Only quite recently I found that I can press C-c ' in such a code block to edit them in a mode-specific little buffer… something new and obvious to learn every day.

Anyhow, to get the nice zenburn-output in the generated HTML, you can use the following CSS (note, so far I have only done the code blocks):

/* zenburnesque code blocks in for html-exported org mode */

pre.src {
   background: #3f3f3f; color: #dcdccc; 
}

.org-preprocessor {
   color: #8cd0d3;
}

.org-preprocessor {
   color: #8cd0d3;
}

.org-variable-name {
   color: #f0dfaf;
}

.org-string {
   color: #cc9393;
}

.org-type {
   color: #dfdfbf;
   font-weight: bold;
}

.org-function-name {
   color: #8cd0d3;
   font-weight: bold;
}

.org-keyword {
   color: #f0dfaf;
   font-weight: bold;
}

.org-comment {
   color: #7f9f7f;
}

.org-doc {
   color: #afd8af;
}

.org-comment-delimiter {
   color: #708070;
}

.org-constant {
   color: #dca3ac;
   font-weight:bold;
}

.org-builtin {
   color: #7f9f7f;
}

You can save the above CSS-blob in a file (say, zenburn-code.css), and set the style sheet for the org-html export by putting a #+STYLE:-line in your org files:

#+STYLE: <link rel="stylesheet" type="text/css" href="zenburn-code.css" />

emacs 23.2

2010-05-14T20:22:00.001+03:00

Recently, emacs version 23.2 was released. It's a quick update after 23.1 came out (July 29 of 2009); it seems Chong Yidong / Stefan Monnier (interview) are doing releases more often than before they took over emacs maintainership. A welcome change, I would say.

The amount of changes is obviously also a bit smaller than in 23.1, but there are still some interesting updates. Let's go through a couple of those here; I am not striving for completeness, and I won't really go into the biggest change (inclusion of the CEDET IDE-framework), as I haven't been using that enough to say anything about it. Instead, let's look at some of the other highlights; for the full list of changes, please refer to the NEWS-file. If you have some other cool new feature that deserves mentioning, please add a comment.

Some highlights

Maximum file size increased to 512Mb (this used to be 256 on 32-bit machines). This may be useful for big log files etc. It does take a while to load such big files, but after that it's not too slow, at least if you have enough RAM. For 'normal' files, you're unlikely to ever hit the limit; e.g. Tolstoy's War and Peace is only 3 MB…
Note, you can set large-file-warning-threshold to set the maximum file size after which emacs will starting asking you for confirmation when trying to open (eh, visit) files.
By default, the mouse cursor turns invisible when typing, so there is no more need for mouse-avoidance-mode and similar tricks. However, if you insist on seeing the mouse cursor, you can add to your .emacs:

(setq make-pointer-invisible nil)

On X-based systems, emacs now listens for font changes (Xft), and can automatically use the GNOME mono-spaced font (as set in the GNOME Appearance preferences dialog). Note that this may not work for all fonts/settings (at least in my tests, setting the font to italic does not seem to reflect in emacs). Anyway, to enable this, put the following in your .emacs (or the moral equivalent):

(setq font-use-system-font t)

On Unix, Emacs 23.2 now follows the freedesktop trash specification for file deletion; thus, the hacks we hacks we mentioned before are no longer needed.
Some cool additions for Tramp, allowing emacs to access files in rsync and even imap://-locations. On systems supporting GVFS, emacs can now directly use e.g. obex://-uris (Bluetooth). I need to play a bit with these things! Tramp support has also been built into eshell.
There are already quite some ways to do auto-completion in emacs using the TAB-key, and emacs 23.2 makes this a bit easier to set up. You can add basic auto-completion with:

(setq tab-always-indent 'complete)

After setting that, the TAB-key will (after trying if there's anything to indent first) provide possible completions. It works pretty well for Emacs-Lisp (I did not test other languages), although the way it shows the completions (separate *Completions*-buffer) is a bit clumsier that what for instance yasnippet or company-mode do.
You can also do partial completions now, by appending initials to the completion style, i.e.:

;; there must be a more elegant way...
(setq completion-styles (append completion-style '(initials)))

With this, you can complete on the initials of functions and variables in the minibuffer, say, typing C-h v tai and then pressing TAB will give you tab-always-indent.
As mentioned, the biggest change is the addition on the CEDET-framework, which contains things like smart completion, code browsing, UML diagram creation, project management – features somewhat similar to those in e.g. Eclipse. I don't know how well it works in practice, but I will give it a try. At least, inclusion in Emacs should make setting it up with all dependencies a bit easier, as there is now a guaranteed-to-work setup for Emacs 23.2 at least.

Summarizing, 23.2 provides us with some nice updates all around and brings CEDET to the masses. Chong Yidong / Stefan Monnier have done a very good job in making faster releases, while still keeping an eye on the quality. On the other hand, the previous version (23.1) is a very solid release, and if you don't need CEDET, there is no real need to hurry to 23.2.

Future releases

A lot is happening in the world of GNU/Emacs, with changes being proposed and implemented in many different places. There's Eli Zaretskii's way work on making emacs support bidirectional languages (for right-to-left writing systems such as Hebrew and Arabic; the /bi/directional part is that one should be able to mix left-to-right and right-to-left). There is Jan DjÃ¤rv's work on adding UI-tabs to emacs (like e.g. Firefox has them). There is Ken Raeburn and Andy Wingo's work on adding Guile Scheme support to emacs - possibly replacing the current Emacs Lisp implementation in the future. These are just a few of the more prominent projects.

Nobody knows in which release these items will be available (if at all), but it's exciting to see all the directions people are taking emacs.

cleaning up the mode-line

2010-05-12T00:02:00.005+03:00

Emacs' version on a status-bar is called the mode-line, and contains all kind of information – the current buffer name, the cursor position and a lot of other things, depending on what major and minor modes are active.

Customizing the mode-line is, unfortunately, rather hard. One day, I'll write something about that… but for now at least we may be able to improve things a little bit, by reducing mode line pollution. Mode line pollution? Well, many parts of emacs like to announce their presence and state in the mode line. With the limited space available there, this can become a bit of an issue, the (Lisp Interaction company Yas abbrev) takes quite some space:

But there are some ways to limit the space taken by modes and minor-modes. Note, these snippets should go in your .emacs, and you need to restart emacs to make them active.

First, the minor modes (note, you can see the currently activated ones with C-h m); install the handy diminish.el (or get it using the emacs-goodies-el package when using Debian/Ubuntu) and add something like the following:

(when (require 'diminish nil 'noerror)
  (eval-after-load "company"
      '(diminish 'company-mode "Cmp"))
  (eval-after-load "abbrev"
    '(diminish 'abbrev-mode "Ab"))
  (eval-after-load "yasnippet"
    '(diminish 'yas/minor-mode "Y")))

And the major-modes, for example for Emacs Lisp mode:

(add-hook 'emacs-lisp-mode-hook 
  (lambda()
    (setq mode-name "el")))

This looks a bit shorter:

You can of course set these names to whatever is obvious to you.

navigating the kill-ring

2010-04-27T22:38:00.003+03:00

The kill-ring is emacs' implementation of a copy-paste-clipboard. As expected, it's more powerful than what most other editors offer - but at the same time, it may be a bit hard to use. We already discussed the kill-ring in the Emacs-Fu prehistory.

One of the more powerful features of the emacs kill-ring is that is allows for multiple entries to be saved there. You can then retrieve those older entries by using prefix arguments, that is: C-y will retrieve the last item from the kill-ring, while M- n C-y will retrieve the n ^th last stretch of 'killed' (cut/copied) text. For example, M-2 C-y will retrieve the second last one.

Unfortunately, for most people it's quite hard to remember what was 'killed' and when and in what order… Those people can of course use the menu (Edit/Paste from kill menu), but that is not always so convenient, requires mousing around etc.

Edit: As Anynomous mentions in the comments, one can of course use M-y to circle through the candidates. This is quite useful, esp. when you have only a few items in the ring. Note, this command only works just after a 'yank' (C-y).

browse-kill-ring

Instead, using the handy browse-kill-ring extension, you can open a buffer which lists the contents of the kill ring, and you can move your cursor to the desired item and insert it.

Installation in simple; first get the browse-kill-ring package from EmacsWiki, or, alternatively, Debian/Ubuntu users can install the emacs-goodies-el-package.

Then, add to your .emacs something like:

(when (require 'browse-kill-ring nil 'noerror)
  (browse-kill-ring-default-keybindings))

Now, the M-y key binding will activate browse-kill-ring iff the normal behavior (see above) is not available, i.e., when the last command was not a 'yank'. You can also edit the kill-ring (press C-h m when in the browse-kill-ring-buffer to see the available bindings).

a little pop-up menu

While browsing EmacsWiki, I found another trick:

(global-set-key "\C-cy" '(lambda ()
   (interactive)
   (popup-menu 'yank-menu)))

After which C-c y will show a little pop-up menu with the your kill-menu entries. It does not seem to fully synchronize with the (possibly edited) entries you get from browse-kill-ring, but it's a pretty neat way to navigate through your kill-ring-buffers – if you don't have too many of them (if so, you could customize the kill-ring-max variable).

creating custom modes the easy way with generic-mode

2010-04-18T20:35:00.003+03:00

Syntax highlighting is useful when editing configuration files, programs and so on, as it helps to prevent errors and makes it easier to quickly scan documents.

Emacs supports syntax highlighting (font locking in emacs lingo) for many different file types. For many common cases (e.g. editing for many programming languages, org-mode), emacs' support goes much further than merely colorizing keywords, and offers all kinds of 'magic' (auto-completion, 'electricity', special key bindings, …). For some other file types, at least keywords are given some different color.

Still, there are files that are not recognized by emacs as having some special format; these are displayed as plain text. This may be the case for less-common configuration files, or your own specific formats.

Defining a full 'mode' for such file types can be a lot of work. Fortunately, emacs offers a easier way: generic-mode. generic-mode defines a whole lot of mode of modes for common formats, but also defines the define-generic-mode macro to create your own modes.

Suppose we have a little language called foo; a typical foo-file might look something like:

!! this is a comment
account=foo; !! another comment
user=jimmy;
password=$3cre7;

Using define-generic-mode, we can easily define a mode for this:

(require 'generic-x) ;; we need this

(define-generic-mode 
  'foo-mode                         ;; name of the mode to create
  '("!!")                           ;; comments start with '!!'
  '("account" "user" 
    "password")                     ;; some keywords
  '(("=" . 'font-lock-operator)     ;; '=' is an operator
    (";" . 'font-lock-builtin))     ;; ';' is a a built-in 
  '("\\.foo$")                      ;; files for which to activate this mode 
   nil                              ;; other functions to call
  "A mode for foo files"            ;; doc string for this mode
)

Now, this will look something like this (if necessary, see the colorized version):

!! this is a comment
account = foo; !! another comment
user = jimmy;
password = $3cre7;

the zenburn color theme

2010-04-04T13:48:00.001+03:00

A popular way to customize emacs is changing its color scheme, as already discussed color theming. Until recently, I was using an evolved version of the color theme presented there, 'djcb-dark'. It works for me but, admittedly, it's a bit ugly.

But recently, in a post to the Wanderlust mailing list, someone mentioned a color theme called Zenburn. Zenburn started its life as a color scheme for vim, around 2002. The explicit goal was to have a pleasant theme that is light on the eyes, and allows you to stay 'in the zone' for long stretches of time. People liked it, and version for many other programs were made, including emacs.

I've been using Zenburn for the last few weeks, and I really like it. I used to think that 'low-contrast' would mean that things are not really clear; but the opposite seems true. Anyway, the screen shot says more than a thousand words I suppose…

Zenburn-for-emacs (written by Daniel Brockman) can be found at the link above. I've sent my updates to him of course, but as it may take a while for the 'official' version to be updated, I've put my version on Emacswiki: ZenburnColorTheme. The changes are the support for Wanderlust, hi-line (for highlighting the current line) , magit and elscreen; also, I made selected (eh, transiently marked regions) not loose their foreground color.

Note, the theme is not yet part of the color-theme package, but does require it.

showing the buffer position in the mode-line

2010-03-20T13:34:00.001+02:00

I do quite a bit of scrolling in emacs, but I hardly ever use the scroll bar for that. The main reason for still having the scroll bar is that it gives me some indication where I am in the buffer. Of course, there is some information in the mode-line, and you can get some more with size-indication-mode, but it's not as immediately obvious as the scroll bar.
But recently, I discovered Lennart Borgman's sml-modeline, which combines all of the scroll bar information into a nice visual indication on the modeline, and I have been happily using it, and got rid of my scroll bar.
Put you sml-modeline in your load-path, and the following fragment in your .emacs should do the trick:

(if (require 'sml-modeline nil 'noerror)    ;; use sml-modeline if available
  (progn 
    (sml-modeline-mode 1)                   ;; show buffer pos in the mode line
    (scroll-bar-mode -1))                   ;; turn off the scrollbar
  (scroll-bar-mode 1)                       ;; otherwise, show a scrollbar...
  (set-scroll-bar-mode 'right))             ;; ... on the right

Note, there is a older version available in Emacswiki which has some problems (such as conflicting with the Standard ML editing mode for emacs); thus, for now it's better to us the Launchpad version; the instructions above apply to that version.

cleaning up buffers automatically

2010-03-08T20:24:00.001+02:00

Recently, I discussed some ways to deal with large numbers of buffers. Maybe we can also take a step back and ask why we have so many buffers in the first place - do we really need all of them?

Well, the obvious answer is: probably not. After a few days of (emacs-uptime) there are all kinds of temporary output buffers, man pages and unchanged buffers you haven't touched in a long time. Let's get rid of those!

midnight

For this very purpose, emacs provides midnight-mode (as has done so for more than a decade). At midnight, it looks at all the buffers, and determines which of the buffers are no longer in use, and closes ('kills') them. Regardless of its name, this cleanup does not necessarily have to take place at midnight, but could be invoked at any time.

Setup is easy, just put the following in your .emacs:

(require 'midnight)

Clearly, the package was designed for emacs instances that are running for long times – for example, by default it clears buffers after having been inactive for 3 days. I'm not sure if that use case is very common today. Anyway, you can change it by setting clean-buffer-list-delay-general (which takes the number of days before a buffer becomes eligible for killing).

You can ask midnight-mode to clean-up unused buffers right now with M-x clean-buffer-list. Also, you can use some variables to control which buffers are to be killed, and which ones specifically not:

clean-buffer-list-kill-buffer-names
clean-buffer-list-kill-never-buffer-names
clean-buffer-list-kill-regexps
clean-buffer-list-kill-never-regexps

To run clean-buffer-list every n minutes or so, you could use run-at-time, left as an exercise to the reader.

tempbuf

Another way to accomplish roughly the same is TempbufMode.

It seems a bit better equipped for shorter cleanup interval, and you have some killed. However, that requires you to add it to the modes where you'd like to more influence on the algorithm it uses to decide whether a buffer may be use it, something like:

;; download tempbuf: http://www.emacswiki.org/emacs/tempbuf.el
(when (require 'tempbuf nil 'noerror) 
  (add-hook 'custom-mode-hook 'turn-on-tempbuf-mode)
  (add-hook 'w3-mode-hook 'turn-on-tempbuf-mode)
  (add-hook 'Man-mode-hook 'turn-on-tempbuf-mode)
  (add-hook 'view-mode-hook 'turn-on-tempbuf-mode))

Side-note: I'm using the (when (require 'tempbuf nil 'noerror) ... ) pattern here to make sure that my .emacs also works when tempbuf is not available.

Added: for cleaning-up your buffer list non-automatically, you can simply use M-x kill-some-buffers. (Thanks Susan!). Or you can use C-x C-b.

wanderlust iii

2010-02-23T20:06:00.003+02:00

Wanderlust

I have been using the Wanderlust E-mail client for almost a year now, and I am very happy with it. In previous postings I already discussed setup and some tips and tricks; and I also had somewhat related posts on bbdb (the address book) and warning you about new mail. But I think it's time for an update.

maintenance

One question that I have received quite a few times was about the maintenance of Wanderlust; it's may be a nice e-mail client, but little seems to have happened in the last few years. It's reasonable concern.

Fortunately, it seems the situation has improved significantly. There's more traffic on the mailing lists, both from old and new users. Various improvements are circulating; the place to get the latest stuff is in David Abrahams' git-repository: semi, flim, apel and wanderlust. The plan is to gradually apply the changes to the upstream (CVS) repository.

bugs

Although I have been quite happy with Wanderlust, there was one bug #5534 that has bitten me a few times, causing occasional hangs when saving (draft) messages with non-ascii characters. It seemed finally to be a bug in emacs itself, which is triggered by something in Wanderlust. A fix will probably be available for the next emacs version; until then, you can work around this by using an external MIME-encoder. To do this, add the following to your WL initialization code (thanks to various helpful people on the WL mailing list):

(setq mel-b-ccl-module nil)
(setq mel-q-ccl-module nil)
(setq base64-external-encoder '("mimencode"))
(setq base64-external-decoder '("mimencode" "-u"))
(setq base64-external-decoder-option-to-specify-file '("-o"))
(setq quoted-printable-external-encoder '("mimencode" "-q"))
(setq quoted-printable-external-decoder '("mimencode" "-q" "-u"))
(setq quoted-printable-external-decoder-option-to-specify-file '("-o"))
(setq base64-internal-decoding-limit 0)
(setq base64-internal-encoding-limit 0)
(setq quoted-printable-internal-decoding-limit 0)
(setq quoted-printable-internal-encoding-limit 0)

(setq-default mime-transfer-level 8)
(setq mime-header-accept-quoted-encoded-words t)

This requires the mimencode-program, which is part of the metamail-package. For the time being, this seems to be the best solution when using Wanderlust with Emacs 23.

one more trick: reformatting

Let's finish with one more trick. Sometimes, incoming mail is formatted quite badly; in particular, the new lines are too long for comfortable reading. From the WL-mailing list, here's a trick to deal with that:

(require 'filladapt)

;; from a WL mailing list post by Per b. Sederber
;; Re-fill messages that arrive poorly formatted
(defun wl-summary-refill-message (all)
  (interactive "P")
  (if (and wl-message-buffer (get-buffer-window wl-message-buffer))
      (progn
        (wl-summary-toggle-disp-msg 'on)
        (save-excursion
          (set-buffer wl-message-buffer)
          (goto-char (point-min))
          (re-search-forward "^$")
          (while (or (looking-at "^\\[[1-9]") (looking-at "^$"))
            (forward-line 1))
          (let* ((buffer-read-only nil)
                 (find (lambda (regexp)
                         (save-excursion
                           (if (re-search-forward regexp nil t)
                               (match-beginning 0)
                             (point-max)))))
                 (start (point))
                 (end (if all
                          (point-max)
                        (min (funcall find "^[^>\n]* wrote:[ \n]+")
                             (funcall find "^>>>>>")
                             (funcall find "^ *>.*\n *>")
                             (funcall find "^-----Original Message-----")))))
            (save-restriction
              (narrow-to-region start end)
              (filladapt-mode 1)
              (fill-region (point-min) (point-max)))))
        (message "Message re-filled"))
    (message "No message to re-fill")))

(define-key wl-summary-mode-map "\M-q" 'wl-summary-refill-message)

Now, you can refill your messages with M-q when in the Summary.

If you have any other nifty WL-tricks that could be useful for others, please share them in the comments, thanks!

dealing with many buffers: ibuffer

2010-02-19T07:53:00.003+02:00

If you are like me, you'll open a lot of buffers in emacs. There may be a couple of buffers with source code, a few for e-mail. org-mode will open buffers for all your agenda files. Then, maybe an info page, a few ERC-channels, a couple of special emacs buffers such as **Messages** and **scratch**. So, in a moderately busy emacs session there may 30-40 buffers open, and after a day or so there can be many more.

With so many buffers, it can be hard to quickly find the one you are looking for - and clearly a one-tab-per-buffer (like Firefox uses) would not work very well either.

So, what can we do instead? Here, on emacs-fu, we discussed this a couple of
times already:

using ido-mode, you can quickly switch to buffers by typing a subset of
their name
using elscreen to step through buffer configurations (this comes close to a
workable tab-like solution)

These are really useful tools. What's still missing though, is a way to get an overview of all buffers. For that, emacs provide buffer-menu, normally bound to C-x C-b. It lists all your buffers, and you can interact with them in a way similar to dired, e.g. you can switch to a buffer by moving the point (cursor) to the buffer and pressing Return. Or you mark buffers for deletion by pressing d when point is on the buffer, and then press x to kill them all.

Very useful. But if you really have a lot of buffers, just having a long list of them may still be a bit hard to deal with. For that, there is ibuffer, which allows you to put your buffers in different categories -- which can even overlap. Emacs ships ibuffer since version 22, so you'll probably already have it.

Using a setup like the following, you can put your buffers in categories; each buffer is shown only once (apparently, the first match), and you can match on mode (the Emacs-mode of the buffer), name (the buffer name), filename (the full path to the file being visited, if any), and a couple of others (see EmacsWiki).

(require 'ibuffer) 
(setq ibuffer-saved-filter-groups
  (quote (("default"      
            ("Org" ;; all org-related buffers
              (mode . org-mode))  
            ("Mail"
              (or  ;; mail-related buffers
               (mode . message-mode)
               (mode . mail-mode)
               ;; etc.; all your mail related modes
               ))
            ("MyProject1"
              (filename . "src/myproject1/"))
            ("MyProject2"
              (filename . "src/myproject2/"))
            ("Programming" ;; prog stuff not already in MyProjectX
              (or
                (mode . c-mode)
                (mode . perl-mode)
                (mode . python-mode)
                (mode . emacs-lisp-mode)
                ;; etc
                )) 
            ("ERC"   (mode . erc-mode))))))

(add-hook 'ibuffer-mode-hook
  (lambda ()
    (ibuffer-switch-to-saved-filter-groups "default")))

If you like ibuffer, you can even override the buffer-menu key binding for
it:

(global-set-key (kbd "C-x C-b") 'ibuffer)

As with buffer-menu, you can do various funky things with those buffers, and also filter them further; see the documentation. I am mostly using it for its buffer-navigational qualities, and it's good at that.

interactive replacement

2010-02-08T00:44:00.002+02:00

I recently found an interesting little package called iedit.el, which allows
you to interactive replacements on multiple strings at the same time. That is,
as you do one replace, you can see how all the same matches being replaced as
you type. It's hard to explain in words, you just have to try it out.

So, how to install this package?

First, download the package (see the link above)
Put it in a directory where emacs can find it; for example,
~/.emacs.d/elisp. If you haven't done so already, you can tell emacs to look in that directory by adding to your .emacs:
```
(setq load-path (cons "~/emacs.d/elisp/" load-path))
```
Then, tell emacs to load this specific module; you can add
```
(require 'iedit)
```
to your .emacs to load it (alternatively, you could use the autoload facility)

then, define a key binding for this:

(define-key global-map (kbd "C-;") 'iedit-mode)

Now, search for some strings that appears multiple times in your buffer, select it,
press C-; (Ctrl+;), and watch how all other matching strings are
changing at the same time.

Very nice.

duplicating lines and commenting them

2010-01-21T21:37:00.003+02:00

Someone on the Emacs Help mailing list asked for an easy way to duplicate a line
and, optionally, comment-out the first one.

Let's first look at simple duplication of a line. This is a common operation,
and vi-users might use something like Yp for that. In emacs, one way to do
this is by typing C-a C-k C-k C-y C-y, which is actually not as bizarre as
it looks if you try it. When using slick copy, as explained in another post,
it's as easy as M-w C-n C-y; and of course it's easy to define a shorter key
binding.

repeat after me
repeat after me

However, neither of these methods works correctly when you're on the last line
of the buffer (by default at least). Also, it puts the point (cursor) below
the duplicated line, while I'd like to put it at the start of it. It seems we
need something a little smarter.

While we're at it, let's also consider the second question: commenting-out the
first line of the duplicates. This is a quite common thing to do when writing
programs or configuration files; you want to try the effect of a small
variation of a line, but want to keep the original so it can be restored when
the variation turns out not to be as good as expected.

/* for (;;) fork (); */
for (;;) fork ();

I hacked up something quickly to solve both questions, and it has evolved a
little bit since – to answer both of the questions. The bit of weirdness in
the end is because of the special case of the last line in a buffer. It
defines key bindings C-c y for duplicating a line, and C-c c for
duplicating + commenting – but of course you can change those.

(defun djcb-duplicate-line (&optional commentfirst)
  "comment line at point; if COMMENTFIRST is non-nil, comment the original" 
  (interactive)
  (beginning-of-line)
  (push-mark)
  (end-of-line)
  (let ((str (buffer-substring (region-beginning) (region-end))))
    (when commentfirst
    (comment-region (region-beginning) (region-end)))
    (insert-string
      (concat (if (= 0 (forward-line 1)) "" "\n") str "\n"))
    (forward-line -1)))

;; or choose some better bindings....

;; duplicate a line
(global-set-key (kbd "C-c y") 'djcb-duplicate-line)

;; duplicate a line and comment the first
(global-set-key (kbd "C-c c") (lambda()(interactive)(djcb-duplicate-line t)))

rectangles and cua

2010-01-16T18:54:00.003+02:00

CUA-mode is a minor-mode that enables the use of Ctrl-X/C/V for cut/copy/paste, as is customary in many computer programs. Of course, it's a bit different in emacs, as it predates CUA and all of those programs. With esp. Ctrl-X (C-x) being in heavy use as a prefix-key already, it's unlikely to change.

CUA-mode has a clever trick to solve that problem – C-x for cut only works when a selection is active, and when no other key is pressed shortly. Otherwise, C-x behaves as usual. This works quite nicely, but personally, I don't use it, as I already have the Emacs key bindings in my muscle memory. Still, it can be useful for people migrating from other CUA-based editors. See e.g. CuaMode for more information.

However, apart from the C-x-trick, CUA also has some nice functionality for rectangular selections. These are sometimes quite useful, and during emacs-fu's prehistory there was already an article about it. The method there works, but with CUA, it is much easier.

So, let's turn it on; put the following in your .emacs:

(setq cua-enable-cua-keys nil) ;; only for rectangles
(cua-mode t)

Now, just put your cursor anywhere, and press C-RET (Ctrl + Enter). You have now started a rectangular selection! There rest is pretty straightforward, you can cut, copy and paste with the normal Emacs key bindings..

I could go into more detail, but the best way is to see it in action in this wonderful screen cast by Mark Mansour. I especially like the way you can add numbered lists.

automatically checking your spelling

2009-12-30T17:09:00.002+02:00

When I'm typing fast, it's easy to make spelling mistakes (as you may have noticed reading Emacs-Fu). It's not so much that I don't know how to write things, but sometimes there seems to be a bit of a disconnect between brain and fingers.

One tool that helps me to make fewer mistakes is automatic spelling checking, and in particular on-the-fly spelling checking. Spell-checking in emacs is taken care of by the ispell-package. Traditionally, this was a way to interface emacs with the ispell-program on Unix, but nowadays it's often used with other programs, such as aspell.

aspell is GNU's intended replacement for ispell, and has been for a long time. In the meantime, other spelling checkers have come up; in the Free Software world, the most prominent one is probably hunspell, which is used by e.g. Mozilla and OpenOffice. As I said, Emacs supports all of those; I'm using aspell, which works well for me. To use aspell for spelling-checking, I have the following in my .emacs:

(setq ispell-program-name "aspell"
  ispell-extra-args '("--sug-mode=ultra"))

Please consult the aspell documentation for the details.

You can spell-check your text with ispell-buffer and friends, which are also available through the menu (Tools/Spell Checking/...). This works fine, but it makes spelling checking a separate step you have to go through and you may forget. So, I like to do the spelling-checking on-the-fly, that is, while I am typing. This can be done using flyspell-mode (you can also use flyspell-prog-mode, to do spell checking inside comments in computer programs, but I find that a bit over the top).

When flyspell-mode is enabled, it will mark misspelt eh misspelled words by painting them in a different color while you are typing -- the common way many word processing programs do it. A common way to enable flyspell-mode is to put it the the mode-hook for the modes where you want to use it. For example, to enable flyspell-mode for all your org-mode buffers, you can add something like the following to your .emacs:

(add-hook 'org-mode-hook
  (lambda()
    (flyspell-mode 1)))

Note, you can use the middle mouse button to get alternatives for a misspelled word.

By default, it uses the English dictionary, but it's easy to switch to another using M-x ispell-change-dictionary. To make it easier, I have defined the C-c N key binding to activate Dutch-language ("nederlands") spelling checking, and update the buffer.

(global-set-key (kbd "C-c N") 
  (lambda()(interactive)
    (ispell-change-dictionary "nederlands")
    (flyspell-buffer)))

Now, there's another category of mistakes – their-they're-there, its-it's or to-too-two that require a spelling checker that's a bit smarter. There are some free implementations in OpenOffice and Abiword; it'd be interesting to see if those could be integrated with emacs as well.

Now, laugh about the sweet irony of the spelling errors that I failed to notice :)

scrolling

2009-12-13T15:46:00.002+02:00

Scrolling It's an integral part of just about any graphical user interface, including emacs. However, I always found that the default way scrolling works in emacs left something to be desired. It puts the scroll bar on the left (!), and when scrolling around, it does not scroll smoothly, but instead it seem to do so in bursts. But, this being emacs, we can change it!

First, the position of the scroll bar. Presumably for historical reasons, emacs puts the scroll bar on the left of the window, unlike most other programs. We can easily change that, by putting the following in .emacs (or ~/.emacs.d/init.el):

(set-scroll-bar-mode 'right)

Instead of right, you can also use left, or nil to hide the scroll bar completely. You can also do this through the menu (Options / Show/Hide / Scroll bar). Note that on X, when the cursor (point) reaches the end of the document, the slider on the scroll bar may not be at the bottom; I understand this is because of some disagreement between Emacs and the toolkit (GTK+ in this case).

Now, what about the other issue, the non-smoothness when scrolling with the cursor-keys or with C-n, C-p? Below are my settings for making scrolling a bit smoother, and the explanation. Of course, these are just my personal preferences.

(setq
  scroll-margin 0                  
  scroll-conservatively 100000
  scroll-preserve-screen-position 1)

The scroll-margin. This determines when scrolling should start; by setting it to 0, emacs will start to scroll whenever you are entering the top or bottom line of the window. You can also this to, say, 5 to let scrolling start whenever you're getting closer than 5 lines from top or bottom
Then, scroll-conservatively determines how far the cursor is allowed to be distanced from the center of the screen when scrolling start. The default sets this to 0, which means that whenever you start scrolling, the cursor jumps to the center of the screen. I find that quite annoying, so I set it to some big number (the 'effective maximum' for that is lines-in-window / 2, but you can put any bigger number there to avoid the jumpiness)
scroll-preserve-screen-position tries to maintain the current screen position when you scroll using Page-Up/Page-Down. I like that.

There are also the variables scroll-up-aggressively and scroll-down-aggressively. Normally, they determine how far emacs will scroll (up and down, respectively) when it does so. However, they don't make any difference with a big scroll-conservatively like I am using. Still, if you want to play with it, their values are fractions between 0.0 and 1.0 (inclusive); a value of 1 means that it will move a full screen when scrolling starts, a value of 0.0 causes a move of only one single line.

changing the cursor color and shape dynamically

2009-12-06T20:17:00.008+02:00

When typing some text, it's often useful to know what mode we're in – are we in overwrite-mode, in read-only-mode, or in normal insert-mode. The information is available in the mode-line – but wouldn't it be nicer to get some small visual cue, for example by changing the cursor color or style?

That indeed is possible. There are some existing ways to do this, described in EmacsWiki. However, I want to be able to control both the cursor color and cursor shape, and also distinguish between overwrite, read-only and 'normal' mode. Below is my attempt.

By putting the following snippet in your .emacs, the cursor becomes a yellow vertical bar during normal mode, it becomes a red block when you're in overwrite-mode and it becomes a gray vertical bar when you're in read-only mode.

;; Change cursor color according to mode; inspired by
;; http://www.emacswiki.org/emacs/ChangingCursorDynamically
(setq djcb-read-only-color       "gray")
;; valid values are t, nil, box, hollow, bar, (bar . WIDTH), hbar,
;; (hbar. HEIGHT); see the docs for set-cursor-type

(setq djcb-read-only-cursor-type 'hbar)
(setq djcb-overwrite-color       "red")
(setq djcb-overwrite-cursor-type 'box)
(setq djcb-normal-color          "yellow")
(setq djcb-normal-cursor-type    'bar)

(defun djcb-set-cursor-according-to-mode ()
  "change cursor color and type according to some minor modes."

  (cond
    (buffer-read-only
      (set-cursor-color djcb-read-only-color)
      (setq cursor-type djcb-read-only-cursor-type))
    (overwrite-mode
      (set-cursor-color djcb-overwrite-color)
      (setq cursor-type djcb-overwrite-cursor-type))
    (t 
      (set-cursor-color djcb-normal-color)
      (setq cursor-type djcb-normal-cursor-type))))

(add-hook 'post-command-hook 'djcb-set-cursor-according-to-mode)

You can change the colors and cursor types by modifying the various variables.

I should probably turn this into a proper minor mode, but for now this seems to work well.

making buffer names unique

2009-11-29T14:52:00.002+02:00

When you open a file in emacs, the buffer gets the name of that file. That's all fine, but what if you open multiple files with the same name? At least for me, it's a fairly common to have a number of different Makefile.am buffers Makefile.am<3> etc., but that does really help to find the right one at the same time. Emacs does make those names unique – Makefile.am<2>, quickly.

To do that, emacs provides uniquify – it makes buffer names unique. In your .emacs:

(require 'uniquify) 
(setq 
  uniquify-buffer-name-style 'post-forward
  uniquify-separator ":")

This is emacs, so you can influence the way in which the names are made unique. I prefer post-forward, and as separator I use a : rather than the default |. Note, instead of post-forward there are other bizarre styles, please see the documentation.

Anyway, now, when opening ('visiting') files test/a/foo and test/b/foo, their buffers get the names foo:a and foo:b. In other words, the name followed by a colon and part of the path. I think it's much clearer than the default names foo and foo<2>. One could ask why emacs should not use uniquify as its default behavior; it seems a clear improvement.

Uniquify is a small convenience that's been a documented part of emacs for 20 years. Still, somehow I missed it until this year. I suspect I am not the only one - which is why I write this.

showing pop-ups

2009-11-19T20:10:00.007+02:00

Updated: yes, it's %s, not %d Sometimes, it's nice when emacs can warn you when something is happening or should happen. For example, when a new e-mail has arrived, or when there's a meeting in 15 minutes you should attend.

As always, there are different way to do this, but here's what I've been using for while. Various versions of this have been circulating around mailing lists, so I don't know whom to credit with the original idea – anyway, this is the (modified) version that I'm using.

(defun djcb-popup (title msg &optional icon sound)
  "Show a popup if we're on X, or echo it otherwise; TITLE is the title
of the message, MSG is the context. Optionally, you can provide an ICON and
a sound to be played"

  (interactive)
  (when sound (shell-command
                (concat "mplayer -really-quiet " sound " 2> /dev/null")))
  (if (eq window-system 'x)
    (shell-command (concat "notify-send "

                     (if icon (concat "-i " icon) "")
                     " '" title "' '" msg "'"))
    ;; text only version

    (message (concat title ": " msg))))

A couple of notes:

I'm using notify-send for sending notifications; this assumes you are using that system (it's part of the libnotify-bin package in Debian/Ubuntu). You can of course replace it with whatever is available on your system. Alternatives are zenity or kdialog or xmessage (for old-timers) and their equivalents (?) on Windows, MacOS.
I'm now using mplayer for playing sounds. This is a bit heavy, but at least plays all kinds of audio files. If you only care about .wav-files, you could replace it with e.g. aplay;
as always, please ignore my ego-centric function names :-)

Now, we can use this function by evaluation e.g.

(djcb-popup "Warning" "The end is near"
   "/usr/share/icons/test.png" "/usr/share/sounds/beep.ogg")

showing pop-ups from `org-mode` appointments

The above popup function is most useful when it's does its work based on some event. To be notified of appointments and the like, there is the emacs appt facility. Here, we set up this appt, and then hook it up with org-mode, so appt can warn us when there's something happening soon…

;; the appointment notification facility
(setq
  appt-message-warning-time 15 ;; warn 15 min in advance

  appt-display-mode-line t     ;; show in the modeline
  appt-display-format 'window) ;; use our func
(appt-activate 1)              ;; active appt (appointment notification)
(display-time)                 ;; time display is required for this...

 ;; update appt each time agenda opened

(add-hook 'org-finalize-agenda-hook 'org-agenda-to-appt)

;; our little façade-function for djcb-popup
 (defun djcb-appt-display (min-to-app new-time msg)
    (djcb-popup (format "Appointment in %s minute(s)" min-to-app) msg 
      "/usr/share/icons/gnome/32x32/status/appointment-soon.png"

      "/usr/share/sounds/ubuntu/stereo/phone-incoming-call.ogg"))
  (setq appt-disp-window-function (function djcb-appt-display))

Of course, you can freely choose a icon / sound to your liking.

showing pop-ups for new mail

Another event you might want to be warned about is new mail. There is something to be set for not letting yourself be disturbed for new mail, but if you sufficiently filter your mails before they enter your inbox, it can be a good way to periodically bring you back from your deep sl ^H^H thinking. For Wanderlust, I use something like this:

(add-hook 'wl-biff-notify-hook
    (lambda()
      (djcb-popup "Wanderlust" "You have new mail!"
        "/usr/share/icons/gnome/32x32/status/mail-unread.png"
        "/usr/share/sounds/ubuntu/stereo/phone-incoming-call.ogg")))

Exercise for the reader: adapt this for your chosen mail client.

copying lines without selecting them

2009-11-12T21:03:00.004+02:00

When I'm programming, I often need to copy a line. Normally, this requires me to first select ('mark') the line I want to copy. That does not seem like a big deal, but when I'm in the 'flow' I want to avoid any little obstacle that can slow me down.

So, how can I copy the current line without selection? I found a nice trick by MacChan on EmacsWiki to accomplish this. It also adds ta function to kill (cut) the current line (similar to kill-line (C-k), but kills the whole line, not just from point (cursor) to the end.

The code below simply embellishes the normal functions with the functionality 'if nothing is selected, assume we mean the current line'. The key bindings stay the same (M-w, C-w).

To enable this, put the following in your .emacs:

(defadvice kill-ring-save (before slick-copy activate compile) "When called
  interactively with no active region, copy a single line instead."
  (interactive (if mark-active (list (region-beginning) (region-end)) (message
  "Copied line") (list (line-beginning-position) (line-beginning-position
  2)))))

(defadvice kill-region (before slick-cut activate compile)
  "When called interactively with no active region, kill a single line instead."
  (interactive
    (if mark-active (list (region-beginning) (region-end))
      (list (line-beginning-position)
        (line-beginning-position 2)))))

It also shows the power of Emacs-Lisp with the defadvice-macro – see the fine documentation. Using defadvice, you can 'decorate' any function with your own modifications. This great power should be used with caution, of course, as to not break other usage that assumes the undecorated versions. In this case, that seem unlikely. And note that the 'advise' only applies when the functions are called interactively.

bookmarks

2009-11-05T21:52:00.002+02:00

Emacs has a very useful system for bookmarks – shortcuts to often-used files. It's also one of those features I only really started using after years of emacs – there seem to be many of such obvious features…

Bookmarks are especially handy if you have long file names, or for examples the special file names for editing root-owned files discussed here before.

To start using bookmarks effectively, there are only a few important key bindings to memorize: C-x r m ('make') will create a new bookmark, defaulting to the current file. Then, you can jump to an existing bookmark with C-x r b ('bookmark') Finally, you can see the list of your bookmarks with C-x r l ('list').

There are a few customizations you can put in your .emacs:

(setq 
  bookmark-default-file "~/.emacs.d/bookmarks" ;; keep my ~/ clean
  bookmark-save-flag 1)                        ;; autosave each change)

editing files owned by root with tramp

2009-10-21T23:08:00.008+03:00

One of the times when many emacs-users still reach for vi is when editing system configuration files – the stuff in /etc/, etc. I think that is because of the now mostly false impression that emacs startup is slow, and because people don't want to run an open-ended program as emacs as root.

There is truth in that last point – but it applies just as well to, say, vim. Anyway, running emacs as root is not a good idea.

So how what can we do it? Easy! Using the tramp package (included with GNU/Emacs since version 22), you can run emacs as a normal user, but edit root-and-other-owned files. It does its magic using sudo, but you won't normally notice. It does require you to have sudo-rights of course.

How does this work? Well, instead of

C-x C-f /etc/hosts

to open a file as a normal user, you use:

C-x C-f /sudo:root@localhost:/etc/hosts

or even shorter, as noted by Alexander Kojevnikov (because Tramp defaults to root@localhost):

C-x C-f /sudo::/etc/hosts

It asks for a password - and you should use your user password for that (not the root password!). This usually works fine, but due to way Tramp works, it can get confused if root has some very weird command prompt. If so, you of course configure tramp. Also note that sudo usually remembers that you logged in, an does not require you to re-enter you password when opening ('visiting') another file for some time period – but you can change this. See the sudo(8).

This automatically invokes tramp which does all the magic for you. If you don't like the somewhat longer (pseudo)paths for files, you can of course use the emacs bookmarks facilty. After you load the file, you can use it like any other file.

Note, this is only of the many useful things you can do with Tramp. Tramp was actually written for editing files on remote machines (using ssh or other protocol), and I very happily used it to edit files on some European machine whilst in Australia. It caches the file locally, and only sends it over when you save it, so it very fast – it simply makes you forget your file is so far away.

writing presentations with org-mode and beamer

2009-10-18T15:22:00.009+03:00

[Updated:fixed an error in the template] Things have been a bit quiet at Emacs-Fu lately; this is mostly because I have been very busy with work, traveling, traveling for work etc. Emacs-wise, this has been a very intensive time, and I have been able to move more and more task to emacs – both professionally and privately. This is mostly because thing become easier when I can do all my things in one place.

Anyhow, one of the tricks I picked up recently is to write presentations with the combination of org-mode and a LaTeX-package called beamer. The most common tool for doing presentations is Microsoft's Powerpoint program. It gets a lot of criticism, most famously from prof. Tufte in his Powerpoint is Evil essay. Of course, the problem is in misuse of the tool, not so much the tool itself.

Still, I didn't want to use Powerpoint (or Powerpoint-wannabees, like OpenOffice's Impress). For the technically-inclined, the knee-jerk reaction to this kind of problem is to shout 'LaTeX!'. Indeed - the LaTeX text-processing system offers a package called Beamer, which allows you to write presentations with LaTeX. It is quite powerful, and even allows for all kinds of fancy graphical bling (fade-in, fade out etc.); even better, it generates PDF-files, which can be viewed just about anywhere. The various themes and color settings it offers are quite nice, even though they tend to fill only a small corner of the design-universe…

beamer and org-mode

Now, while I am no stranger to LaTeX, especially for writing a quick presentation, it can be a painful to remember the various directives and options. I am not really a daily LaTeX-user, so I tend to forget these things. I am a daily org-mode user though, and org-mode can export to LaTeX (which then, in turn, are translated into PDFs). So why not use org-mode to generate presentations?

It turns out that that is quite easy.

First, we need to define some of the LaTeX-boilerplate, and tell org-mode about it, so we never need to think about it again. Put the following in your .emacs:

;; allow for export=>beamer by placing

;; #+LaTeX_CLASS: beamer in org files
(unless (boundp 'org-export-latex-classes)
  (setq org-export-latex-classes nil))
(add-to-list 'org-export-latex-classes
  ;; beamer class, for presentations
  '("beamer"
     "\\documentclass[11pt]{beamer}\n
      \\mode<{{{beamermode}}}>\n
      \\usetheme{{{{beamertheme}}}}\n
      \\usecolortheme{{{{beamercolortheme}}}}\n
      \\beamertemplateballitem\n
      \\setbeameroption{show notes}
      \\usepackage[utf8]{inputenc}\n
      \\usepackage[T1]{fontenc}\n
      \\usepackage{hyperref}\n
      \\usepackage{color}
      \\usepackage{listings}
      \\lstset{numbers=none,language=[ISO]C++,tabsize=4,
  frame=single,
  basicstyle=\\small,
  showspaces=false,showstringspaces=false,
  showtabs=false,
  keywordstyle=\\color{blue}\\bfseries,
  commentstyle=\\color{red},
  }\n
      \\usepackage{verbatim}\n
      \\institute{{{{beamerinstitute}}}}\n          
       \\subject{{{{beamersubject}}}}\n"

     ("\\section{%s}" . "\\section*{%s}")
     
     ("\\begin{frame}[fragile]\\frametitle{%s}"
       "\\end{frame}"
       "\\begin{frame}[fragile]\\frametitle{%s}"
       "\\end{frame}")))

  ;; letter class, for formal letters

  (add-to-list 'org-export-latex-classes

  '("letter"
     "\\documentclass[11pt]{letter}\n
      \\usepackage[utf8]{inputenc}\n
      \\usepackage[T1]{fontenc}\n
      \\usepackage{color}"
     
     ("\\section{%s}" . "\\section*{%s}")
     ("\\subsection{%s}" . "\\subsection*{%s}")
     ("\\subsubsection{%s}" . "\\subsubsection*{%s}")
     ("\\paragraph{%s}" . "\\paragraph*{%s}")
     ("\\subparagraph{%s}" . "\\subparagraph*{%s}")))

This is based on the template by Thomas S. Dye on the org-mode mailing list. You can of course add other packages to it with \usepackage. In my version, I have add the Listings-package for including syntax-highlighted snippets of source code in my presentations. Importantly, I added the [fragile] options to the frame-settings, otherwise you cannot include such source code fragments without LaTeX complaining in various unhelpful ways.

Note, you can customize the way the Listings package works by changing the template above; or by setting the options in the org-file; this involves some 'raw LaTeX' though. It might make sense to define some macros for that.

Now, we can easily make a presentation in org-mode; simply start the file with something like:

#+LaTeX_CLASS: beamer
#+MACRO: BEAMERMODE presentation
#+MACRO: BEAMERTHEME Antibes
#+MACRO: BEAMERCOLORTHEME lily
#+MACRO: BEAMERSUBJECT RMRF
#+MACRO: BEAMERINSTITUTE Miskatonic University, Astrology Dept.
#+TITLE: Presentation with Org-Mode and Beamer
#+AUTHOR: Someone

Of course, you can change these parameters; for example, you might want to change the BEAMERTHEME into Madrid or Warsaw, or … – see the Beamer User Guide (PDF).

After having set up these things, you can write presentations in the familiar org-mode mark-up.

including source code

As mentioned before, you can use the listings-package to include source code snippets in your presentation. You'd write this something like:

#+BEGIN_LaTeX
\begin{lstlisting}[language=c]
for (int i = 1; i != 10; ++i) 
    std::cout << i << ": hello, world!"
              << std::endl;
\end{lstlisting}

#+END_LaTeX

In other words, we include some 'raw' LaTeX to do this. Now, the org-mode-way of doing this, would be to use something like

#+BEGIN_SRC c
  /* code */
#+END_SRC

as discussed before. This works well when exporting to HTML, but at this moment this will simply translate into a verbatim environment in LaTeX - so we use lstlisting to get some syntax-highlighting.

including pictures

Of course, the full arsenal of org-mode tools is available as well, for example Ditaa, as discussed before. Ditaa is now shipped as part of org-mode, and you can use it to create picture which are then included in your presentation. Very nice.

For including existing images (PNGs, JPGs etc.), it's probably easiest to put use some raw LaTeX for that, e.g., something like

#+LaTeX:\includegraphics{/some/path/emacs.png}

putting it together

Now, let's put it all together. Below is an example presentation. Assuming you have everything installed (ie., LaTeX with the listings package, a fairly recent org-mode, ditaa), you create your presentation.org and then press C-c C-e d and your presentation (presentation.pdf) is generated and automatically shown in your PDF-viewer. Easy!

The intermediate files (such as presentation.tex) are there as well, so you can check them if something went wrong.

I have uploaded the resulting PDF to Slideshare, so you can see what it looks like. However, the Slideshare-converted version is extremely blurry, unlike the crisp PDF I actually created. I'd be happy to upload the file somewhere else if someone can point me to a good place, thanks!

So hopefully this shows that you can quite easily make presentations with org-mode, with some help from Beamer, LaTeX etc. Beamer actually provides a lot more, such as funky slide-transitions and other tricks – but the things here should give you a good starting point.

#+LaTeX_CLASS: beamer
#+MACRO: BEAMERMODE presentation
#+MACRO: BEAMERTHEME Antibes

#+MACRO: BEAMERCOLORTHEME lily
#+MACRO: BEAMERSUBJECT RMRF
#+MACRO: BEAMERINSTITUTE Miskatonic University, Astrology Dept.
#+TITLE: Presentation with Org-Mode and Beamer
#+AUTHOR: Someone

* My presentation

** Overview

   1. Introduction

   2. Main part

   3. Questions
    
    
** Some interesting stuff
    
*** an important point
    
    - subpoint a
      
    - subpoint b

** Graphics

*** a picture

#+begin_ditaa blue.png -r -S
+---------+
| cBLU    |
|    +----+
|    |cPNK|
+----+----+
#+end_ditaa

*** another picture
#+LaTeX:\includegraphics{emacs.png}

** More interesting stuff

*** some C++ code
#+begin_LaTeX
\begin{lstlisting}[language=c]
for (int i = 1; i != 10; ++i) 
    std::cout << i << ": hello, world!"
              << std::endl;
\end{lstlisting}
#+end_LaTeX

*** and some Python...

#+begin_LaTeX
\begin{lstlisting}[language=python]
for i in range(1,10):
        print i, "hello, world!"
\end{lstlisting}
#+end_LaTeX

wanderlust tips and tricks

2009-09-19T12:24:00.002+03:00

Earlier, I spoke of the wonderful Wanderlust e-mail client. After years of using mutt, I am a quite happy Wanderlust-user now. Now, it's few months since my conversion, time to discuss some of the customizations I did. Not all the defaults are so well-chosen (in my opinion), but fortunately, the package is very configurable.

If you are interested in Wanderlust, this entry might save you some time in figuring out such customizations and some other tricks. If you haven't done so before, I'd recommend you to read the older entry first. Also, the entry about BBDB may be useful.

Before going into the customizations, let me first answer a question I got asked a couple of times: why I am using Wanderlust and not, say, VM, gnus, Mew or even mutt or some other client?

To start with the last part, an emacs-based client fits in very well with my workflow, which is (duh) revolves around emacs. Doing my email there as well makes a lot of sense - a little return-on-investment for the time spent taming emacs and its bag of tricks.

The reason I particularly like Wanderlust, is that it works very well with mail stored in maildirs - as you may know, maildir is a one-file-per-message way of storing your mail on disk. That's great for backing up things, and sync'ing different machines.

Unlike VM and gnus, Wanderlust keeps the mail in the maildir as-is, and does not use a separate spoolfile – thus, all changes are reflected in the maildir itself, making it possible to use different clients (ie., use mutt when needed). Even more important, the wonderful tool offlineimap does two-way synchronization with IMAP-servers, and downloads everything into a maildir. So, I can download all the mail on my laptop machine, go offline and work on the messages (delete, move, reply etc.) during a flight, and when I'm back online, I can synchronize things. All this 'cloud'-stuff is nice, but I like to have my mails on my side of the intertubes.

Ok, now let's take a look at some of the customizations and tricks. All of these are little snippets to add to your ~/.wl-file.

Forwarded mails should use 'Fwd:', not 'Forward:'

I wonder why this is not the default.

(setq
  wl-forward-subject-prefix "Fwd: " )    ;; use "Fwd: " not "Forward: "

Reply-to-all should not be the default

By default, Wanderlust uses Reply-to-All; that is usually not what we (well, I) want. The code below makes Reply-to-Sender the default, with Reply-to-All behind C-u; ie. A or a will reply to sender, C-u A and C-u a reply to all.

(Note, the uppercase A is for replying with quoting the original message, while the lowercase version starts the reply with an empty message)

;; from a WL-mailinglist post by David Bremner

;; Invert behaviour of with and without argument replies.
;; just the author
(setq wl-draft-reply-without-argument-list
  '(("Reply-To" ("Reply-To") nil nil)
     ("Mail-Reply-To" ("Mail-Reply-To") nil nil)
     ("From" ("From") nil nil)))


;; bombard the world
(setq wl-draft-reply-with-argument-list
  '(("Followup-To" nil nil ("Followup-To"))
     ("Mail-Followup-To" ("Mail-Followup-To") nil ("Newsgroups"))
     ("Reply-To" ("Reply-To") ("To" "Cc" "From") ("Newsgroups"))
     ("From" ("From") ("To" "Cc") ("Newsgroups"))))

Setting up spam-handling

If you're using spamassassin for spamfiltering, you can quite easily integrate it with Wanderlust:

(require 'wl-spam)
(wl-spam-setup)
(setq elmo-spam-scheme 'sa)   ;; sa for spamassassin, see the elmo-spam-scheme
                              ;; docs for alternatives
(setq wl-spam-folder ".spam") ;; maildir to store spam

After this, you quite easily handle spam in the 'Summary' with some keybindings:

k C : check whether spamassassin considers this message 'spam'
k m : mark message(s) as spam (move to spam folder)
k n : learn this message is 'ham'
k s : learn this message is 'spam'

Note, there are some hooks for other spamfiltering solutions as well.

How to easily refile messages

I receive all my messages in only two mailboxes: one for personal mail, and one for mailing lists. If, after reading, I want to keep the message, I'll refile it to some other folder (after all, it's good to empty your mailboxes quite often. Wanderlust makes this refiling quite easy; the first way is to do it semi-automatic, i.e., let Wanderlust 'guess' the folder for you, based on the contents of the message. Then, when pressing 'o' in the summary, it will suggest this folder, and you can refile (move) the message. You can set up this 'guessing' something like this:

(setq
  ;; refile rules determine the default where mails are put

  ;; when you mark them for refiling ('o'); cfg. save-hooks in mutt
   wl-refile-rule-alist  
  '(
     ("Subject" ;; put more specific rules before more general ones.
       ("emacs"   . ".emacs")   ;; emacs-related mail

       ("running" . ".running") ;; running-related mail
       )
     
     (("To" "Cc" "Delivered-To") 
       ("myself@company.com"      . ".workmail") 
       ("myself@home.com"         . ".privatemail"))
     
     (("Precedence" "Priority")
       ("bulk\|1\|2\|list"       . ".bulkmail"))))

Explicit refiling

Semi-automatic refiling works fairly well, but you might also want to have some explicit shortcuts to move messages to specific folders. For example, to move message from your inbox to your Project X-folder, or your Project Y-folder.

(defun djcb-wl-summary-refile (&optional folder)
  "refile the current message to FOLDER; if FOLDER is nil, use the default"
  (interactive)
  (wl-summary-refile (wl-summary-message-number) folder)
  (wl-summary-next)
  (message (concat "refiled to " folder)))

(define-key wl-summary-mode-map (kbd "b x") ;; => Project X

  '(lambda()(interactive)(djcb-wl-summary-refile ".project-x"))) 
(define-key wl-summary-mode-map (kbd "b y") ;; => Project Y
  '(lambda()(interactive)(djcb-wl-summary-refile ".project-y")))

Assuming you have (Maildir) folders project-x and project-y.

Check outgoing mail

It's not uncommon to forget to add a subject or an attachment when you send a mail (or at least, when I send a mail…). However, using wl-mail-send-pre-hook we can let Wanderlust warn us when something like that happens.

;; suggested by Masaru Nomiya on the WL mailing list

(defun djcb-wl-draft-subject-check ()
  "check whether the message has a subject before sending"
  (if (and (< (length (std11-field-body "Subject")) 1)
        (null (y-or-n-p "No subject! Send current draft?")))
      (error "Abort.")))


;; note, this check could cause some false positives; anyway, better
;; safe than sorry...
(defun djcb-wl-draft-attachment-check ()
  "if attachment is mention but none included, warn the the user"
  (save-excursion
    (goto-char 0)
    (unless ;; don't we have an attachment?

      (re-search-forward "^Content-Disposition: attachment" nil t) 
     (when ;; no attachment; did we mention an attachment?
        (re-search-forward "attach" nil t)
        (unless (y-or-n-p "Possibly missing an attachment. Send current draft?")
          (error "Abort."))))))

(add-hook 'wl-mail-send-pre-hook 'djcb-wl-draft-subject-check)
(add-hook 'wl-mail-send-pre-hook 'djcb-wl-draft-attachment-check)

Ok, that's all for now… I'll get back to Wanderlust in the future; of course, feel free to add your own tricks in the comments-section.

managing e-mail addresses with bbdb

2009-08-16T21:32:00.002+03:00

BBDB, the Insidious Big Brother Database is an Emacs addressbook application that works particularly well with e-mail. It's one of the classic emacs packages, written in 1991 by Jamie Zawinski.

Personally, I do not use BBDB as a general address book. Instead, I use it to harvest the e-mail addresses of the people that send me mail, so that the next time I'd like to send e-mail, I can auto-complete the names / e-mail addresses. If you're not using some emacs-based email client, BBDB might not be that useful in practice.

Note that other people are using BBDB for much more, see the Emacswiki-entry for some examples of that. Here, I just give some basics to get you started; please refer to the fine manual for all the details.

configuration

So, after you've installed bbdb (just follow the instructions; alternatively Ubuntu/Debian users can simply install the bbdb package), we can add the following to .emacs to set it up:

(setq bbdb-file "~/.emacs.d/bbdb")           ;; keep ~/ clean; set before loading
(require 'bbdb) 
(bbdb-initialize)
(setq 
    bbdb-offer-save 1                        ;; 1 means save-without-asking

    
    bbdb-use-pop-up t                        ;; allow popups for addresses
    bbdb-electric-p t                        ;; be disposable with SPC
    bbdb-popup-target-lines  1               ;; very small
    
    bbdb-dwim-net-address-allow-redundancy t ;; always use full name
    bbdb-quiet-about-name-mismatches 2       ;; show name-mismatches 2 secs

    bbdb-always-add-address t                ;; add new addresses to existing...
                                             ;; ...contacts automatically
    bbdb-canonicalize-redundant-nets-p t     ;; x@foo.bar.cx => x@bar.cx

    bbdb-completion-type nil                 ;; complete on anything

    bbdb-complete-name-allow-cycling t       ;; cycle through matches
                                             ;; this only works partially

    bbbd-message-caching-enabled t           ;; be fast
    bbdb-use-alternate-names t               ;; use AKA


    bbdb-elided-display t                    ;; single-line addresses

    ;; auto-create addresses from mail
    bbdb/mail-auto-create-p 'bbdb-ignore-some-messages-hook   
    bbdb-ignore-some-messages-alist ;; don't ask about fake addresses
    ;; NOTE: there can be only one entry per header (such as To, From)
    ;; http://flex.ee.uec.ac.jp/texi/bbdb/bbdb_11.html

    '(( "From" . "no.?reply\\|DAEMON\\|daemon\\|facebookmail\\|twitter")))
)

This will set up BBDB for you. I have commented the various settings; you can of course get more information for each of them by putting your cursor on them (in emacs) and issuing C-h v.

integration with e-mail clients

Another important part is the integration with e-mail - which is why I am using BBDB in the first place.

As I mentioned before, I am using the wonderful Wanderlust e-mail client for emacs, and you can easily integrate it with BBDB by putting the following in your .wl-file:

(require 'bbdb-wl)
(bbdb-wl-setup)

;; i don't want to store addresses from my mailing folders
(setq 
  bbdb-wl-folder-regexp    ;; get addresses only from these folders
  "^\.inbox$\\|^.sent")    ;; 


(define-key wl-draft-mode-map (kbd "<C-tab>") 'bbdb-complete-name)

For gnus, you'd use something like:

(add-hook 'gnus-startup-hook 'bbdb-insinuate-gnus)

(I am not using gnus myself, feel free to add you setup in the comments)

The BBDB-manual has the details for some other mail clients as well.

Use

So, we have everything set up now – but how does it work? Well, whenever you read e-mails, BBDB stores the various e-mail addresses. Whenever you write an e-mail, you can complete the names with M-x bbdb-complete-name, by default bound to M-TAB. This keybinding conflicts with many window managers, which already use M-TAB (Alt-TAB) for window switching. So, it's useful to rebind it to something else, for example C-TAB (I already did that for Wanderlust, in the example above).

I don't use BBDB too much directly, but you can manipulate the address; first display one with M-x bbdb-display-address, they you can edit a field by pressing 'e', 'd' for deleting the field or record, C-o for adding a new field and so on – see the whole list.

interview with Chong Yidong and Stefan Monnier

2009-08-03T19:55:00.004+03:00

Earlier this year, Chong Yidong and Stefan Monnier took over Emacs maintainership from Richard Stallman, and they successfully completed the Emacs 23.1 release. I asked them a couple of questions about the process, Emacs-development and some of the plans for the future.

I'd like to thank Chong (CYD) and Stefan (SM) to take the time to answer my (djcb) questions and even more so for doing an excellent job bringing us Emacs 23!

djcb: First of all, could you tell us a bit about yourself? For example, what you do when not hacking on Emacs?

CYD: I'm a postdoc in theoretical physics, specializing in photonic crystals and other optical phenomena.

SM: I'm a professor at the University of Montréal, teaching and researching theory of computer languages. More specifically, I design new type systems and try and abuse existing type systems for "type based formal methods" purposes.

djcb: Earlier this year, the two of you took over the maintainership of Emacs from Richard Stallman. How did you get involved in hacking on Emacs? How has the transition gone?

CYD: My first involvement in Emacs-related development was around 2004 or 2005—very recent by Emacs hacker standards—when I found myself with some free time on my hands after college. At that time, I wrote wikipedia-mode, a major mode for editing Wikipedia articles, plus some word-wrapping code that eventually became longlines-mode, and patches to emacs-devel fixing a few minor bugs. My level of involvement gradually grew, until eventually I was helping Richard to roll the pretest tarballs for the Emacs 22 release.

Because I was quite active in the Emacs 22 release process, I've been pretty comfortable with my role in Emacs 23. It helps, of course, that many parts of Emacs have their own dedicated and experienced maintainers, e.g. the major Lisp packages such as CC-mode, Gnus, and Org-mode.

SM: I started hacking on Emacs a fairly long time ago when I was waiting to start my PhD, but it only got more serious during my PhD when I decided that PCL-CVS was a neat idea but unusable as it stood (for lack of maintainership). It all went downhill from there.

The transition to maintainership happened very smoothly. I had already considered maintaining Emacs when Gerd [ Gerd Moellmann ] left (i.e. when 21.1 was released; at which point Richard ended up regaining maintainership for lack of any other volunteer), but it was a pretty busy time for me, so I decided not to. This time Richard kept a very active role, which coupled with the help of Chong made it very pleasant.

There's a fair bit of pressure, of course, because it's a very old package, so people have a lot invested in it, making some changes terribly delicate. As a maintainer, I did get to steer the direction of Emacs development, tho mostly by my own contributions and by imposing some contentious new defaults. The role of a maintainer as I see it is mostly to make sure the package keeps its integrity.

But I have to say, that while Chong started maybe a bit more of a "rookie maintainer" than I, he quickly took over and he deserves much of the credit for 23.1, while I was too busy with my work to do much good.

djcb: Talking about Emacs development: there are of course many people involved. Can you give a estimate of how many?

CYD: There are about 120 people who have commit access to the code repository; of these, I think around 20 contribute regularly. This does not count the packages that are maintained separately from Emacs.

Additionally, we do of course receive a steady stream of small patches from various users.

Emacs 23 has just been released (on July 29 2009), congratulations, a great accomplishment indeed! From your perspective, what are the most important improvements in Emacs 23 for end-users? And what about the internals? Are there any big changes in the way Emacs operates?

CYD: I'd describe the Emacs 23 release cycle as dominated by internals changes, in contrast with Emacs 22, where most of the major improvements occurred at the Lisp level. There are two fundamental changes. First, the internal character representation is now Unicode-based, which simplifies various aspects of multilingual editing. Second, the font engine has been revamped, and, among other things, we now support anti-aliasing on X. Both these changes are due largely to Kenichi Handa, who deserves a huge amount of credit for patiently developing the code a period of years.

One other major internals change is a restructuring of the terminal interaction code, by Károly Lőrentey, which allows a single Emacs process to display on X and text terminals simultaneously. Building on this "multi-tty" code, Dan Nicolescu implemented a small but clever hack, allowing Emacs to run as a daemon serving emacsclient connections.

There are several Lisp-level changes, large and small. For instance, Stefan revamped the minibuffer completion code, which is now more sophisticated about generating completions. And there are, as usual, new modes and packages: Doc-view mode, Ruby mode, nXml mode, etc.

SM: Better support for Unicode, and better support for fonts, multi-tty support, plus lots of new modes as always. Of course, I'm very happy with my new completion code, which makes partial-completion-mode obsolete (and enabled by default).

The new support for Unicode and for fonts required significant changes. Big thanks to Kenichi Handa for most of that.

djcb: Are there any features that you would have liked to add, but that were somehow not yet ready?

CYD: One feature that I'd have liked to include into 23.1 is CEDET, a set of packages by Eric Ludlum (the author of Speedbar), which turns Emacs into an IDE. There was no time to merge it for 23.1, but hopefully it will be included in 23.2.

SM: Several packages were planned for inclusion, but didn't make it. Support for GNUstep was planned (and is actually in there) but doesn't work. Also I hoped the new VC code would be developed further, but it sadly stayed at the stage where it mostly provides the same features as the old one (with all kinds of improvements in the way it supports them, tho).

djcb: There is always a bit of tension in Emacs between keeping things as they are, and changing things to be more like other programs - for example when thinking about key bindings and various defaults. What is your take on this? Should Emacs try to accommodate new users, or instead try to keep things as they are?

CYD: My impression is that I'm a little more conservative than Stefan with regards to changes, though I'm not sure what he thinks ;-) That said, we seem to arrive at the same conclusions with surprising frequency.

SM: Emacs standard key bindings (like C-x and C-c prefixes) clash badly with "standard" key bindings of other apps, so I don't think there's much hope to make Emacs like other applications. But yes, I generally believe that, all things being equal, it's better to be like others than to be different in this respect. But since changing bindings (or behaviors) is disruptive, I only consider it worthwhile if I believe the new default is really superior (not just for new users).

djcb: For example, in Emacs 23, transient-mark-mode is the default, but delete-selection-mode is not. How do you decide such things?

CYD: Typically, we try not to make flashy changes. The transient mark mode change is the exception that proves the rule: transient-mark-mode is so useful, and is so widely used (even Richard uses it), that it doesn't make sense to leave it off by default. But the rule of thumb is to improve Emacs on Emacs' own terms; for instance, CUA mode will not become the default anytime soon, I think.

SM: transient-mark-mode is an enabler: it allows some commands to behave differently depending on the activation state of the region. So it's a clear improvement. delete-selection-mode is not as important in this regard. We may see something along the lines of delete-selection-mode at some point, tho probably something more minor that only caters to the few cases where delete-selection-mode is more than just a way to avoid hitting C-w.

djcb: How do you see the competition with other text editors? Do you look for ideas elsewhere? Is there any other editor you would be using if Emacs did not exist?

CYD: I'm afraid I don't pay much attention to other editors.

SM: I used Zmacs, XEmacs, and Epoch at some point. That's about it. I do like structured editors, and I think Emacs should and will move in this direction (with more parsing going on).

djcb: It's a bit premature of course, but it's always interesting to speculate a bit about the future. Do you have any particular post-Emacs-23 plans? Obviously, this all depends on what people come up with, but are there any directions you would like Emacs to go?

CYD: The present plan is for Emacs 23.2 to contain a small number of new features, in addition to bugfixes. As mentioned above, I'd like to try to include CEDET. In general, I hope to move to shorter, more disciplined release cycles. Emacs 23 was a good step in that direction, as it was shorter than the previous cycle.

SM: My main goal for Emacs-23 was to shorten the release cycle. Hopefully, the quality has not been reduced accordingly. For 23.N there are several improvements planned (or even done), mostly about inclusion of packages like js2-mode and CEDET. In the longer term, the main goals for me are the integration of the lexical-scoped branch, the support for bidirectional display, and adding more parsing technology (basically replace syntax-tables with something like lex & yacc, maybe).

Thanks a lot Stefan and Chong!

emacs 23 has been released!

2009-07-28T23:01:00.006+03:00

Emacs 23(.1) has been released! After only just over two years since the previous version, emacs 23 has been released on July 29 2009. Time to celebrate! And a big thanks all the talented hackers that made it possible!

Emacs 23 brings many new features. Some of those have been discussed before in emacs-fu, and of course you can get the full list from the NEWS-file (C-h n). This is just a list of some of the highlights, in particular the end-user-visible ones. Let's go through them - of course I cannot mention all of them, so feel free to add your favorite one in the comments.

fonts & anti-aliasing

Finally, emacs 23 brings support for anti-aliased fonts to X (Mac/Windows users have had this for a while). If you're running emacs on X, this one change is enough to never want to go back to an older version of Emacs again.

The new font system mentioned in some posts before: setting fonts and emacs 23.

support for D-Bus and Zeroconf

You can now call other services on the desktop using the DBUS IPC system (popular on X); using d-bus: an example shows how to communicate with the Tomboy note taker program from emacs. As more and more desktop services are accessible using D-BUS, this offers great opportunities for better integrating emacs with the rest of the desktop. For example, one could imagine that emacs could communicate with a network manager when it needs a connection. Or it could show a desktop notification when an appointment is near. And all without adding hard dependencies or calling external binaries.

Using Zeroconf is also quite easy; for example, to get a list of all zeroconf-support printers, you could do something silly like:

(require 'zeroconf)
(zeroconf-init)
(dolist (srv (zeroconf-list-services "_printer._tcp"))
  (insert (format "\nprinter: %s" (nth 2 srv))))

to insert a list of the available printers in your current buffer. As with D-Bus, it's really an enabler for a lot of cool things.

support for 'headless' emacs-daemon

If you have a lot of support packages, emacs startup can be a bit slow. However, emacs 23 brings emacs --daemon, which enables you to start emacs in the background (for example when you log in). You can instantly pop up new emacs windows (frames) with emacsclient. Of course, you could already have an emacs 'server' in older versions, but being able to start it in the background makes this a much nicer solution.

The Emacs-daemon was discussed in emacs-fu in emacs –daemon and windows and daemons (for MS-Windows). Popping up new emacs windows is so fast that you can use emacs for any editing job, for example as an editor for an email program, or for quick rememember notes.

You can even combine X and console clients in one session now.

Emacs now support Xembed

This enables you to embed emacs in other programs (on X) using XEmbed. Haven't played with that yet. There is some more information in EmacsWiki/Xembed.

Support for frame opacity

You can now make you emacs frames transparent. Discussed before in transparent emacs. Not sure how useful this is, but it surely looks nice :)

Internationalization

Emacs's character set is a superset of Unicode, with about four times the space available. That should be enough for the foreseeable future… There are also many new character sets available, as well as new language environments, such as Chinese-GB18030, Khmer, Bengali, Punjabi, Gujarati, Oriya, Telugu, Sinhala, and TaiViet.

Note that, internally, emacs uses UTF-8 now.

New defaults

Screen motion now goes by screen lines by default, that is when you move the cursor up or down, it follows the line as you see them. Nice.
Transient mark mode (visible selection) is now on by default, so no need for (transient-mark-mode t) in your .emacs anymore. However, you still need to put (delete-selection-mode t) if you like replace the current selection with your typing.
Also shift-select mode is enabled by default, so you can select with shift + the arrow keys.

New modes and packages, and updated ones

docview-mode enables you to open PDF/DVI/PS files within emacs;
M-x butterfly (see http://xkcd.com/378/)
EasyPG; access GNUPG, available under Tools/Encryption/Decryption
fast line numbers with linum; see showing line numbers;
proced: dired for processes (M-x proced);
remember-mode, for jotting down things to remember; see remember;
ruby-mode, xesam-mode, zeroconf, …
abbrev has been rewritten
gdb can be very fancy now: fancy debugging with gdb;
file deletion can use the system 'Trash'; see using the system's trash when deleting files.

stepping through your window configurations

2009-07-13T22:59:00.002+03:00

As a small addendum to the entry about keeping related buffers together (with Elscreen): there is also winner-mode, as was mentioned by ustunozgur. winner-mode is a bit simpler than Elscreen. It allows you to step through the various window configuration you had before - instead of having separate 'tabs' as in elscreen, you just step through your history.

I have the following in my .emacs:

(require 'winner)
(setq winner-dont-bind-my-keys t) ;; default bindings conflict with org-mode

(global-set-key (kbd "<C-s-left>") 'winner-undo)
(global-set-key (kbd "<C-s-right>") 'winner-redo)
(winner-mode t) ;; turn on the global minor mode

As you see, I am using the windows-key in the key bindings once more, but of course you can use something else as well.

keeping related buffers together with elscreen

2009-07-09T00:14:00.003+03:00

I wrote about switching buffers a couple of times. Switching buffers is one of the things I do a lot when using emacs – switching between e-mail, IRC and some blog entry. Or simply between a couple of source files in a project.

With some of the tricks mentioned, switching buffers can be made pretty easy.

However, what about programs that consist of multiple buffers? For example, my e-mail program (Wanderlust) splits the screen in separate buffers with mail headers, mail folders and the contents of one message. The same for fancy debugging with gdb, or simply when I have split my screen in two (C-x 2) to view two files at the same time. When I then try to switch buffers, only one of the related buffers will be switched – which is usually not what I want.

I'd like to treat a set of related buffers plus their screen layout as a logical unit.

There are different ways to do that in emacs. One obvious way is to use multiple frames (windows). But I prefer to keep everything in one - and I found the that the easiest solution is elscreen.

Installation is simple; download from here, and follow the instructions in the package. I've set up some easy key-bindings in my .emacs:

(load "elscreen" "ElScreen" )

;; F9 creates a new elscreen, shift-F9 kills it
(global-set-key (kbd "<f9>"    ) 'elscreen-create)
(global-set-key (kbd "S-<f9>"  ) 'elscreen-kill)  


;; Windowskey+PgUP/PgDown switches between elscreens
(global-set-key (kbd "<s-prior>") 'elscreen-previous) 
(global-set-key (kbd "<s-next>")  'elscreen-next)

Now, whenever I want to switch to a new task, say, read e-mail, I press F9, and a new elscreen will appear (it's visible as a sort-of 'tab' at the top of your screen), and start e-mail there. I can then switch to other elscreens, and all of them maintain their buffers and window layout. I have found this very useful. There are some more tricks, and some add-on packages, but this should give you a good start.

There is one small item on my todo-list. Example: when I push M-x wl, emacs automatically switches to the Wanderlust-buffer – or starts it. Now, when using elscreen, I'd like to automatically switch to the correct screen instead of switching the current buffer.

keyboard shortcuts

2009-07-03T22:46:00.003+03:00

Emacs has many useful functions, but for the most efficient use you really need to make keybindings (as previously discussed) for the ones you use often. There's no shortage of possible shortcuts, but the number of easy-to-remember bindings is fairly limited.

I can remember bindings that I use all the time like M-w for copy (well, kill-ring-save), or M-q (fill-paragraph) to word-wrap a paragraph, even if they're not that mnemonic (interestingly, it can be hard to verbalize these bindings when someone ask me – but my fingers have no such trouble).

For functions that I use every minute, any weird key binding will do (as long as it is short). And functions that I use seldomly I can look up in a menu. The trouble is with those functions in between :)

Bindings that involve the arrow-keys are attractive, but I've found that e.g. org-mode binds many of those already. And in the olden days, the C-c-prefix was reserved for user-defined key bindings – but again, org-mode and other packages have overtaken that those. So what's left? Recently, I have been using the Windows-key a bit more. Under (my) X, it's bound to super, and emacs does not use it for anything else, so I have been using it to create a set of useful key bindings. I am trying to be a bit systematic, where super + lowercase letter starts some 'application':

(global-set-key (kbd "s-a") 'org-agenda-list) ;; Agenda
(global-set-key (kbd "s-n") 'org-todo-list)   ;; todo-list (nextactions)

;; program shortcuts
(global-set-key (kbd "s-b") 'browse-url)  ;; Browse (W3M)
(global-set-key (kbd "s-f") 'browse-url-firefox)  ;; Firefox...
(global-set-key (kbd "s-t") 'twitter-get-friends-timeline) ;; Twitter
(global-set-key (kbd "s-w") 'wl)            ;; Wanderlust

and super + uppercase opens a file / special buffer, for example:

(global-set-key (kbd "s-S") ;; scratch
  (lambda()(interactive)(switch-to-buffer "*scratch*")))
(global-set-key (kbd "s-E") ;; .emacs
  (lambda()(interactive)(find-file "~/.emacs")))
(global-set-key (kbd "s-G") ;; gtd.org
  (lambda()(interactive)(find-file "~/.emacs.d/org/agenda/gtd.org")))

super + arrow keys I now use for windmove (see here).

The windows-keys are not perfect of course – they don't work from the console (easily) or, ironically, on Windows. But they are mnemonic – I can remember s-t for twitter; contrast this with C-x 5 2 to create a new frame.

So, I wonder, does anyone have some clever scheme for their key bindings? I think I am getting much of the efficiency from emacs from the fact that I can do just about anything with some quick actions on the keyboard, so I'm very interested.

jumping back to past locations

2009-06-25T22:17:00.003+03:00

With the pop-global-mark-command, you can quickly jump back to the locations you were before, like tracking back your bread crumbs.

A typical example of this is when doing some programming and looking up some function in another file, which refers to a function in yet another file, and so on – for example, see navigating through source code using tags.

Press C-x C-SPC (the default key binding for pop-global-mark) to make your journey back to where you came from; it works in a cyclical fashion as well, so you can go on and on.

Quite useful – you may want to use a more convenient key binding though. Admittedly, it's hard to come up with any intuitive keybinding which is not already taken by something else…

setting fonts

2009-06-23T20:26:00.004+03:00

NOTE: if you like Org-Mode, please go and vote for it in SourceForge Community Choice Award – it's in the Most Likely to Change Change the Way You Do Everything-category.

For pleasant working with emacs, one of the more important things is choosing the right font ('face'). Especially within a windowing system, and especially with Emacs 23, there are a lot of possibilities. I am thinking from the Linux/X-Window perspective here – the support for anti-aliased fonts makes things look so much nicer – as discussed before.

On X, there are different ways to set your font. One way is through the menu (Options/Set default font.../). We can also set it in our .emacs, with (set-default-font "<font>"), or using ~/.Xdefaults. The latter method makes emacs-startup quite a bit faster, but this may have become less important in the age of emacs –daemon (Emacs 23).

barb wire

In either case – .emacs or .Xdefaults – you must provide some string describing the font. Up to Emacs-23, under X you had to use the 'barb wire'-style X font description, which you could get from a tool like UI-designers' dream xfontsel; the font description would then look something like:

  -*-bitstream vera sans mono-medium-r-*-*-*-120-*-*-*-*-iso8859-*

emacs 23

In the brave new world of Emacs 23, on X, you can also use the somewhat clearer Fontname-<size> format. You can get a list of the fonts installed on your system with the fc-list commond; if you only want to get the monospaced fonts, use

 $ fc-list :spacing=mono

For details, see the FontConfig user manual.

Note that installing fonts under X is rather easy as well these days; in most cases all you need to do is put the .ttf-files in your ~/.fonts directory and all will be find, although some program might require a restart.

Once you have chosen a font, you can put it in your ~/.Xdefaults:

Emacs.font: Envy Code R-10

and don't forget to run xrdb ~/.Xdefaults afterwards, to tell X about the changes. All of this should happen before you start emacs.

Alternatively, you can put in your .emacs something like:

(if (eq system-type 'windows-nt)
  (set-default-font "-outline-Consolas-normal-r-normal-normal-14-97-96-96-c-*-iso8859-1"))

(if (eq window-system 'x)
  (set-default-font "Inconsolata-11"))

This will set a different default font, based on whether you are running on Windows or X. You can freely adapt it to your own desires of course.

Side note: if there is yellow in the code snippet above, that is because of hightlighting lines that are too long.

face value

There are many fonts; which one is the 'best' for you, obviously depends on personal taste and also what you want to with it. As I use emacs for coding but also for reading e-mails and writing documents, there are some things that are important for me:

monospace
most important: clear and crisp, even when using smaller font sizes;
clearly separate O (capital O) and 0 (zero);
support italic display;
support the characters I might use (incl. accented characters and some greek ones).

Following these rules, I found the Envy Code R font to work very nicely. It's not fully Free though: Free to use but distribution prohibited. Raph Levien's Inconsolata is nice as well and truly Free; it does not provide an italic font though (at least it does not show in Emacs). Here's a list of programming fonts.

Hmmm… I wanted to write some small entry… And there is so much more to say about fonts. As often, EmacsWiki has a lot of information; for example about FontSets, which allow you to use a sort-of combination-font, which is nice if you have to work with mixed character sets (Latin, Arabic, CJK etc.).

Also, the emacs-fu entry on zooming in/out is useful in this context, even though Emacs 23 has gained something similar by default.

Also, the entry on color theming may be interesting, in this entry we only look at the default font, but you can change fonts governing only part of emacs as well; see M-x list-faces-display.

Or get information about the font at point with C-u C-x =.

search and replace in files

2009-06-19T14:18:00.005+03:00

I always try to do more things from within emacs; as said before, it's all about return on investment for all the time spent mastering emacs. One of the things I sometimes still used a separate terminal for, was search and replace of text in files – a quick grep or sed from the command line.

source code: tags

If you're searching (not replacing) symbols in source code, the most convenient way is to use a tagfile. A while ago, I discussed navigating through source code using tags (using GNU Global). I still often see people writing code in emacs, and then opening a terminal open to grep for function names, definition and so on… There is really no need for that; see the linked entry.

The GNU Global tagfile system unfortunately does not have a search-and-replace function; if you are using etags, however, you can use M-x tags-query-replace to replace the symbols in all files in the tagfile.

GNU Global users can of course still use the other search-and-replace mechanisms below.

other files: rgrep

For searching recursively for some strings (regexps) in a file tree, there is the very useful M-x rgrep. It will ask what you want to search for, some pattern for the files to match, and the top of the directory to search.

So, for example, if you want to find all occurences of the string 'FIXME' in txt-files in your ~/Documents directory tree, you would do something like:

M-x rgrep
FIXME
*.txt
~/Documents

and you will get at buffer with all matches. For this, it uses the same kind of buffer you use for compilation, and you can jump to the matching locations just like you can jump to error locations in the compilation output - that is why with M-x next-error you can jump from match to match, even though of course they are not really errors. The default shortcut for next-error is C-x`, but you can of course remap that to something saner, exempli gratia:

(global-set-key (kbd "<M-prior>") 'previous-error) 
(global-set-key (kbd "<M-next>")  'next-error)

so you can use M- with PgUp/PgDown to jump through the matches (or errors).

One final comment about rgrep: in the above example, the FIXME is a regular expression (as discussed in building regular expressions, while the *.txt is a shell pattern (see e.g. the findutils manual).

replacing: dired

If you want to replace text in multiple files, your best bet is to use dired, the emacs file manager.

dired deserves its own entry (and probably more than one), but if we just look at search-replace, the steps are not too hard. Suppose we want to replace all strings FOO with BAR in a bunch of files in ~/myfiles/. We open dired with C-x d, enter ~/myfiles, and a list of the files in that directory appears.

Now, we mark the files we'd like to change by moving the cursor to them and press m (unmark with u). You can also mark filenames matching some regexp with M-x dired-mark-files-regexp (or '* %', obviously) or files containing some regexp with M-x dired-mark-files-containing-regexp (or '* g').

After marking some files, you can use M-x dired-do-query-replace-regexp to interactively replace some regular expression in all of them – you have to press 'y' to confirm the changes. You can quit this process by pressing 'q'.

dired can even work recursively, as an anonymous commenter remarked (thanks!); slightly edited: You can type 'i' to insert a subdirectory to the dired buffer. You can also run M-x find-name-dired or M-x find-dired to generate a dired buffer with the results of the find-command. Then you can mark wanted files and perform query replace with 'Q'. Also see: Emacs Nerdery: Search & replace across files.

As an alternative, you can use an external package like FindR for recursive search & replace. I haven't used that one myself though, as I haven't had the need yet.

emacs-fu feed updated

2009-06-16T23:40:00.005+03:00

At one point in your life, you reach the conclusion that you are not perfect. Even I did :-). For example, some of the Emacs-Fu posts contain errors (typos, out-of-context copy-past etc.), which are usually quickly found by some attentive reader. I do attempt to test things of course, but sometimes things slip through.

Of course, I can quickly fix those mistakes; I do know how to use a text editor after all. The trouble with that is that it provokes aggregators like Planet Emacsen and others to consider this as a new post, which is shown as such on the main page. Of course I don't want to spam the poor Planet Emacsen readers with updates just because I fixed a typo in some old entry.

The problem is not with those aggregators – it's with blogger.com, which does not invoke the right formula to say that something is updated instead of published. And my power to change blogger.com is rather limited.

Blogger does support tag-specific feeds though; so, my workaround is the following:

The feed with all new posts: http://emacs-fu.blogspot.com/feeds/posts/default/-/new
A feed with all updates (this is the current one): http://emacs-fu.blogspot.com/atom.xml

When I update an entry, I will remove the new-tag, so aggregators that use the first feed will not be bombarded with these small changes - and I am planning a few..

So, if you only want to get the new posts, I'd recommend changing to the first feed. Planet Emacsen has already done so (thanks Edward!).

Now keeping my fingers crossed it'll all work as expected...

ERC: the emacs IRC client

2009-06-13T22:37:00.005+03:00

ERC: IRC with emacs

I am migrating more and more of my computer tasks to emacs; I already discussed Twitter and e-mail (with Wanderlust); I'm also using emacs-w3m for some of my web browsing (more about that some other time).

Reason for this ongoing emacsication is to get some return on investment for those countless hours spent on mastering the One True Editor. And it pays off - I can manipulate and glue all these programs together so they fit my workflow like a glove.

Recently, I have also started use emacs for IRC, another great Finnish invention. I am not really an IRC power-user, but I do use; before, I used irssi for that, in a ansi-term console (as explained). But now I have switched to ERC, the emacs IRC-client. You can do just about anything with ERC – I have only barely scratched the surface. But let me share my basic setup.

There first step is getting ERC; it's bundled with any recent emacs, so all you need to do is to add it to your .emacs:

(require 'erc)

That was not too hard, was it?

Now, the thing this is to determine what irc-servers / channels you'd like to join (of course you can do that later manually, but automate what we can). So, we define erc-autojoin-channels-alist:

;; joining && autojoing

;; make sure to use wildcards for e.g. freenode as the actual server
;; name can be be a bit different, which would screw up autoconnect
(erc-autojoin-mode t)
(setq erc-autojoin-channels-alist
  '((".*\\.freenode.net" "#emacs" "#gnu" "#gcc" "#modest" "#maemo")
     (".*\\.gimp.org" "#unix" "#gtk+")))

So, the first element is the IRC-server (with appropriate wildcards), the other elements are channels. This will make ERC automatically join the channels when it notices you're connected to the IRC-server.

And read the comment – it took me some time to figure out why things weren't working. Also, you might want to change these IRC-channels to your own favorites.

The next thing is tracking: ERC can track the various channels you're in, and notify you when there is something new in the channel (it will colorize the channelname in your modeline). This is generally useful, but I don't really care about when people join or leave, or other IRC-meta spam. So:

;; check channels
(erc-track-mode t)
(setq erc-track-exclude-types '("JOIN" "NICK" "PART" "QUIT" "MODE"

                                 "324" "329" "332" "333" "353" "477"))
;; don't show any of this
(setq erc-hide-list '("JOIN" "PART" "QUIT" "NICK"))

Note, the last line has nothing to do with this tracking, that's just telling ERC that I am not interested in those things at all, so it should hide them.

Almost there. Now, I have some function to actually start ERC; it's based on some code in found somewhere, but cannot find right now. The function will start ERC, or switch to it if it's already running – it will actually switch to the most recently active ERC-buffer, which makes things a bit easier to manage.

(defun djcb-erc-start-or-switch ()
  "Connect to ERC, or switch to last active buffer"
  (interactive)
  (if (get-buffer "irc.freenode.net:6667") ;; ERC already active?

    (erc-track-switch-buffer 1) ;; yes: switch to last active
    (when (y-or-n-p "Start ERC? ") ;; no: maybe start ERC
      (erc :server "irc.freenode.net" :port 6667 :nick "foo" :full-name "bar")
      (erc :server "irc.gimp.org" :port 6667 :nick "foo" :full-name "bar"))))

Note: don't forget to replace the :server-value as well as foo and bar with your own preferences. It should be clear what they mean…

You can bind this function to some easy key, and things get really convenient; for example:

;; switch to ERC with Ctrl+c e
(global-set-key (kbd "C-c e") 'djcb-erc-start-or-switch) ;; ERC

Once you have started ERC and are connected to some channels, things work pretty much as in any IRC-client. For each channel, a buffer is opened, and from their on it is up to you to have enlightening conversations with other people around the globe…

Once more, I have only barely scratched the surface of ERC. These are just some basic instructions for getting things working. After that, there are a million things you can do; EmacsWiki has an extensive section on it, with more information and customization then you'll probably ever need.

e-mail with wanderlust

2009-06-08T21:35:00.006+03:00

e-mail with wanderlust

(This is part I of entry on the wanderlust e-mail client; part II will appear soon).

Earlier, I have written about how I am using mutt as my e-mailclient. I discussed running mutt inside emacs as well. Of course, mutt is an external program, which puts some limits on its integration with emacs. I did try various emacs-based clients, such as VM (ViewMail) and GNUS, but they always left me a bit unsatisfied.

To start with, it was rather hard to set these programs up – and I am an Emacs-user, I like tweaking things… Still, it was hard to get even simple things working. Maybe I have uncommon wishes, but my desired setup already sent me to the edges of the googleable universe.

But now I have found an emacs-based client that seems to work really well for me. It's called Wanderlust, and it's a fine piece of Japanese engineering. It can be a little bit intimidating to set up at first, even though I found it still much easier than the other emacs-based clients I tried. Anyway, I am sharing a very basic setup here, enough to get you going.

What about my setup? Well: I use maildirs – that is, I download my mail into a local ~/Maildir directory-tree, either with e.g. fetchmail or with offlineimap. It's a particulary nice setup for offline-usage: whenever there's a network connection, I suck up all the mails and have them available offline. I work like this since the days when there was only expensive dial-up access to the net, and later I found it very convenient when I was traveling with a laptop and had only occasional net-access.

So, Maildir access is pretty important for me, and I'll describe my setup for using Wanderlust with it here. If you're using IMAP instead of Maildirs, you might be interested in the Emacs with Wanderlust and GMail-article.

Getting started

So, how to get started with Wanderlust?

In short: install Wanderlust and put some stuff in two files (~/.wl and ~/.folders).

A little bit longer:

get wanderlist - I am using the wl-beta packages from Ubuntu/Debian, which makes this a painless process, but you can also use source packages;
put your Wanderlust-configuration in a special file: ~/.wl;
put a list of the mail folders you're interested in, in a file called

~/.folders. (yes, you can customize all this)

For the rest of the discussion, let's assume we have a Maildir which contains some folders:

inbox for incoming e-mail
bulk for incoming Mailing List mail
drafts for drafts
sent for sent e-mail
trash for junk email

All incoming mail is going to either inbox or bulk. I'm not going to discuss how to get the mails there – I assume you're already have these thing set up; otherwise, you can take a look at tools like fetchmail, retchmail, procmail and friends. Note that much of the discussion here applies as well if you're using Wanderlust with POP or IMAP.

What to put in `~/.wl`?

So, how to setup Wanderlust to use this? Well, our configuration goes into a file called ~/.wl. There's a million more things you can set up here , but let's stick to the basics here. I'll discuss more tricks and extensions later.

;; mode:-*-emacs-lisp-*-
;; wanderlust 
(setq 
  elmo-maildir-folder-path "~/Maildir"          ;; where i store my mail

  wl-stay-folder-window t                       ;; show the folder pane (left)
  wl-folder-window-width 25                     ;; toggle on/off with 'i'
  
  wl-smtp-posting-server "localhost"            ;; put the smtp server here
  wl-local-domain "myhost.example.com"          ;; put something here...
  wl-message-id-domain "myhost.example.com"     ;; ...

  wl-from "Me <me@example.com>"                  ;; my From:

  ;; note: all below are dirs (Maildirs) under elmo-maildir-folder-path 
  ;; the '.'-prefix is for marking them as maildirs
  wl-fcc ".sent"                       ;; sent msgs go to the "sent"-folder
  wl-fcc-force-as-read t               ;; mark sent messages as read 
  wl-default-folder ".inbox"           ;; my main inbox 
  wl-draft-folder ".drafts"            ;; store drafts in 'postponed'
  wl-trash-folder ".trash"             ;; put trash in 'trash'
  wl-spam-folder ".trash"              ;; ...spam as well
  wl-queue-folder ".queue"             ;; we don't use this

  ;; check this folder periodically, and update modeline
  wl-biff-check-folder-list '(".todo") ;; check every 180 seconds
                                       ;; (default: wl-biff-check-interval)

  ;; hide many fields from message buffers
  wl-message-ignored-field-list '("^.*:")
  wl-message-visible-field-list
  '("^\\(To\\|Cc\\):"
    "^Subject:"
    "^\\(From\\|Reply-To\\):"
    "^Organization:"
    "^Message-Id:"
    "^\\(Posted\\|Date\\):"
    )
  wl-message-sort-field-list
  '("^From"
    "^Organization:"
    "^X-Attribution:"
     "^Subject"
     "^Date"
     "^To"
     "^Cc"))

What to put in `~/.folders`?

So, that was the basic setup. Now we need to tell wanderlust about the folders we'd like to see in the user-interface: ~/.folders. Wanderlust does not automatically use all the folder in your ~/Maildir. The folder names in ~/.folders can refer to maildirs, newsgroups, POP-account, IMAP-folders and a couple of other ones. In particular, you can combine folders to show as aggregate folders in Wanderlust.

Wanderlust distinguishes the kind of folder something is by looking at a special prefix character. For maildirs, this is a dot ('.'), IMAP-folders get a '+', newsgroups get a '-' and so on. After the mailbox name, you can have a 'friendly name' in quotes, which is what will show up in the user-interface.

Something like this:

# WL folders (put the '#' always at the beginning of the line)
.inbox     "Inbox"
.bulk      "Mailinglists"
.drafts    "Drafts"
.sent      "Sent Mail"
.trash     "Junk"

Note, the little format has some more tricks; e.g., if you had some folders, you cold have something like:

# WL folders (put the '#' always at the beginning of the line)

# 'Lists' will be a tree node with three elements
Lists {
        .mailinglist1 "A mailinglist"
        .mailinglist2 "Another Mailinglist" 
        .mailinglist3 "Yet one more mailinglist"
}

# you make virtual folders from combined lists with the '*'
AllMyMailingLists  *.mailinglist1,.mailinglist2,.mailinglist3

Anyway, there's plenty of room for experimentation here…

Now, we're ready! Start Wanderlust with M-x wl. You will be greeted, and things are relatively easy from there on. You might want to use the menu at first at least, as the default keybindings are somewhat surprising (like a for reply, and w to compose a new message).

What's next?

As I said, there are 10E6 things to configure and to customize, but this should give you a reasonable setup to start with; you might want to change some details (like the folder names) to match your situation. Good luck!

As a true emacs-mailer, Wanderlust nicely integrates with e.g. BBDB (the addressbook) and org-mode. You can also use GPG (through mailcrypt), spamfiltering, and so on. I will discuss some of those things in the second part of the discussion of Wanderlust.

tetris

2009-06-02T21:54:00.009+03:00

The game of Tetris has turned 25 24. I don't care very much about computer games, but I've nevertheless spent quite a bit of time playing Tetris - its brilliance is in its simplicity.

Obviously, emacs comes with a Tetris-clone; just type M-x tetris RET and there you go! There is very little useful things to customize about the game, except maybe you'd like to keep your ~/ clean and set:

(setq tetris-score-file 
  "~/.emacs.d/tetris-scores")

I'd also like to point to the lisp source code, which is only 658 lines long - almost CodeGolf-worthy. It's an interesting read if you are that kind of person. To see the source code, access the help for M-x tetris, i.e., press C-h f tetris and Enter (as discussed in Helpful Emacs). You'll get a help buffer then, which includes a link to tetris.el, the source code; obviously, you need to have the sources installed. In Ubuntu/Debian, you can install the source code through the emacs22-el or emacs-snapshot-el packages, depending on the version of emacs you're using.

Thanks to emacs, you can actually read the source code in one buffer, while playing tetris in the other one!

finding commands with smex

2009-05-30T22:01:00.004+03:00

If you're like me, you'll usually have a lot of buffers open in emacs. To quickly switch between them, you press C-x b (Ctrl-X and b), and type the beginning of buffer name. This is made much more convenient with e.g. ido (see Switching Buffers) or icicles. They allow you switch to a buffer by typing just some characters appearing anywhere in the buffer name, autocompletion etc.

The question for today is: what to do if am not searching for a buffer or file, but for some emacs command?

Often, I search for a certain command, ie. the ones that come after M-x. After typing M-x there's autocompletion if you know the beginning of the command… but maybe I remember only it was something with string, but exactly how? Was it replace-string or string-replace?

For these deep problems, there is smex (think: search-M-x). smex brings ido-style completion to choosing commands.

After installing the smex package, you can put something like the following in your .emacs:

(setq smex-save-file "~/.emacs.d/smex.save") ;; keep my ~/ clean                                      
(require 'smex)                                                  
(smex-initialize)                                                               
(global-set-key (kbd "M-X") 'smex)

As you can see, I have set the keybinding to M-X, that is (for most people) Alt-Shift-x; of course you could override the normal M-x ('execute-extended-command', note the small x), but usually the normal completion is fine.

Admittedly, smex serves a niche use-case, but I still use it a couple of times a day.

[ Note that packages like icicles and anything can do similar things; they do much more as well, and I haven't had the chance to play with those in detail, so for the time being I stay with smex. ]

tracking changes

2009-05-26T22:33:00.006+03:00

It's sometimes nice to see the changes you've made to a file. If the file is under version control, you can use the 'diff'-features of the version control system of course; or you can use diff-buffer-with-file to compare your buffer with the version on disk. That obviously only. works when you haven't saved the file yet.

Anyway, a bit easier, straighforward way may be to use highlight-changes-mode. With that mode, emacs can give a special color to parts of the text that you have changed.

;; higlight changes in documents
(global-highlight-changes-mode t)
(setq highlight-changes-visibility-initial-state nil); initially hide

The last line tells me that the changes should not be visible unless I want to see them.

I defined a key binding (F6) so I can easily toggle between visible/invisible changes:

;; toggle visibility
(global-set-key (kbd "<f6>")      'highlight-changes-visible-mode) ;; changes
;; remove the change-highlight in region
(global-set-key (kbd "S-<f6>")    'highlight-changes-remove-highlight)

With this last keybinding S-<f6> (Shift-F6), I can remove the change-indication of the current region (selection). Here are some other useful keybindings to quickly jump between various changes:

;; alt-pgup/pgdown jump to the previous/next change

;; if you're not already using it for something else...
(global-set-key (kbd "<M-prior>") 'highlight-changes-next-change)
(global-set-key (kbd "<M-next>")  'highlight-changes-previous-change)

Another interesting thing you can do is M-x highlight-compare-with-file.

The only remaining problem with highlight-changes-mode is that the default colors are, well, hideous. But of course, that can easily be fixed by changing the faces:

(set-face-foreground 'highlight-changes nil)
(set-face-background 'highlight-changes "#382f2f")
(set-face-foreground 'highlight-changes-delete nil)
(set-face-background 'highlight-changes-delete "#916868")

Or adding to your color-scheme:

(highlight-changes ((t (:foreground nil :background "#382f2f"))))
(highlight-changes-delete ((t (:foreground nil :background "#916868"))))

Now, with these color changes, the foreground stays the same, only the background changes a bit. I am using a dark theme, you might want to change the colors to fit in with your theme.

There are some more features - for example, to rotate through changes of different age. For such things I prefer to use a version control system, but you might want to check it out.

Tracking changes can be quite useful. And, unlike some word-processing software, emacs does not hide your highly embarrassing modifications somewhere in your document…

writing and blogging with org-mode

2009-05-21T15:25:00.008+03:00

Already in some previous entry I sang the praises about org-mode, the emacs-mode that is such a nice, flexible way to organize your life. There is so much in org-mode that it's quite hard to fit in here, but thankfully org-mode is documented very well; there's not only the reference manual, there is also a lot of user-provided documentation about how they use org-mode. A nice recent example of that is Bernt Hansen's Org Mode - Organize Your Life In Plain Text!.

I use org-mode for time-management too - I'm using it in a rather simple fashion compared to Bernt Hansen, but find it very useful. I also use org-mode for writing webpages and blogs (like this one), and that is what I'd like to discuss here.

Actually the first time I heard about this org-mode-thing people were raving about, it was for taking notes. Curious as I am, the next time I needed to take notes, I uttered M-x org-mode to try it out, and found how easy and natural it is to write structured, semi-rich-text with org-mode. Some examples:

Markup

I can write headings by starting lines with some stars, the number of stars determining the heading level:

* level 1 heading
  some text
** level 2 heading
   some more text
*** level 3 heading
    even more

org-mode helpfully gives them some different colors; by pressing TAB when I am on a heading, I can hide/show the lower levels and the contents. Nice!

It's also easy to get all the basic markup by decorating your words a bit:

This is *bold* /italics/ _underline_ [[http:/emacs-fu.blogspot.com][Emacs-Fu]]

In org-mode it looks like:

This is *bold* /italics/ _underline_ Emacs-Fu

There are many more things; for example, there's the table editor; I simply type |country|capital|<Enter>|-<Tab> and I get:

| country | capital |
|---------+---------|
|         |         |

Now, I fill in the names in the colums, ending each line with <Alt><Enter> (or M-RET), and org-mode takes care of making everything fit, so we get:

| country     | capital   |
|-------------+-----------|
| finland     | helsinki  |
| netherlands | amsterdam |

You can even insert formulae in the cells, turning this into a simple kind of spreadsheet. Haven't used that yet though.

Blogging

Now, one of the things I use org-mode for is blogging; for that, I need to convert the org-text into HTML; this is simple org-export-as-html (or C-c C-e). I can then copy the HTML into blogger.com or whatever (that might be automatable). You can also export to plain-text, LaTex and other formats.

I found that it makes me a much more productive blogger if can use org-mode; it's so much more convenient to write the mark-up than to write raw HTML. Now, sometimes I might want still want to write some raw HTML, but that can be easily done:

#+BEGIN_HTML
   <button onclick="alert('you are!');">I feel lucky!</button> 
#+END_HTML

in the export HTML this will become: How cool is that?!

However, I only found out about the nicest trick very recently from the org-mailing list.

In this blog, I often use blurbs of code; I'd like to show those blurbs with the syntax-highlighting that emacs gives me. For that, I use the htmlize-package. For example, when showing some Emacs-Lisp code, I would copy that to an Emacs-Lisp buffer, then run htmlize-region on the code, and finally copy the result back in a raw-html block (like the one for the <button>).

I wondered - could I not do that automatically? I could mark code in org-mode as being 'Emacs-Lisp'-code (or Perl, or Python, or …), and when I'd export the html, org-mode would go through the trouble of calling htmlize-region on it and use that in its output. Sounded like a nice idea, I asked for some advise on how to do it.

Five minutes after asking, I got a reply – 'just use #+BEGIN_SRC/#+END_SRC'. Wow – it was already there in org-mode, it's even documented, but somehow I missed that. So, now I can write:

#+BEGIN_SRC perl
   for (my $i = 0; $i != 10; ++i) {
        print "hello, world!\n";
   }
#+END_SRC

#+BEGIN_SRC c++
  for (int i = 0; i != 10; ++i)
        std::cout << "hello, world!" << std::endl;
#+END_SRC

and in the export HTML, this will look like:

for (my $i = 0; $i != 10; ++i) {
      print "hello, world!\n";
}

for (int i = 0; i != 10; ++i)
      std::cout << "hello, world!" << std::endl;

I am impressed.

These were just some of the things I've discovered in the last few months of using org-mode, and I am only scratching the surface. Feel free to share your org-mode-writing tips in the comments :-)

building regular expressions

2009-05-18T22:10:00.005+03:00

This whole entry could be summarized as 'use M-x re-builder' to build your regular expressions. But let's see if I can stretch that wisdom over a couple of lines…

For searching and replacing, regular expressions ('regexps') are a very useful tool. For example, see the entry about getting your ip-number. I am not going to explain regexps here – there are plenty of good references about them. Of course, emacs supports regexps - but it's not always so easy, compaired to e.g. Perl. I am only providing some trivial examples here, please see Steve Yegge's post on the regexp tricks possible with then-new Emacs 22 (I can't remember ever needing that kind of regexp-pr0n in real life though…)

Back to regexps - on of the issues with regexps in Elisp is that they need extra quoting, that is, lots of \-escape characters; regexps can be hard to comprehend, and this does not help… Why the extra quoting? Let's look at a simple example. Suppose we want to search for the word cat. And not category or concatenate. The regular expression would then be \bcat\b.

In Perl you could write this as /\bcat\b\/ (in Perl you specify regexps by putting them between /-characters).

Not so in Emacs-Lisp. On the Lisp-level, there are no regexps; there are only strings and only the regexp functions understand their true nature. But before the strings ever get those functions, the Lisp interpreter does what it does best: interpreting. And when it sees \b, it interprets it as the backspace-character.

To make it not do that, you'll need to pay the 'slash-tax' and write something like:

(re-search-forward "\\bcat\\b")

Things can go ugly quickly from there - think of when you need search for something with a backslash, like our regex \bcat\b itself; you'd need to do:

(re-search-forward "\\\\bcat\\\\b")

slash tax break

To make things even more interesting, in different contexts, different rules apply. The above is all about regexps in strings in Emacs-Lisp. However, things are different when you provide a string interactively.

Suppose you search through your buffer (with M-x isearch-forward-regexp or C-M-s). Now, your input is not interpreted by the Lisp interpreter (after all, it's just user input). So, you're exempt from the slash tax, and you can use \bcat\b to match, well, \bcat\b.

re-builder

So, regexps can be hard, and Emacs-Lisp makes it somewhat harder. A natural way to come up with the regular expression you need, is to use trial-and-error, and this is exactly what isearch-forward-regexp and friends do. But what about the slash-taxed regexps that you need in your Lisp code?

The answer is M-x re-builder. I am sure many people are already using it, but even if there were only one person that finds out about this through this blog-post, it'd be worth it! And this is the whole trick here: whenever you need a regexp in your code, put the kind of string it should match in a buffer, and enter M-x re-builder.

re-builder will put some quotes in the minibuffer. You type your regexp there, and it will show the matches in the buffer as you type. It even supports different regex-syntaxes. By default, re-builder will help you with the strings-in-Emacs-lisp kind of regexps; this is called the read-syntax. But you can switch to the user-input regexps with C-c TAB string RET (yes, these are called string here). There are some other possible syntaxes as well.

One final trick for re-builder is the subexpression mode, that you activate with C-c C-e (and leave with q). You can than see what subexpressions match (ie. if we can match cat, cut, cot etc., with \\bc\$.\$t\\b, and the subexpression would then contain the middle letter. re-builder automatically converts between the syntaxes it supports, so you could use 'string-mode' as well, bc$.$t\b.

using the systems 'trash' when deleting files

2009-05-15T21:03:00.004+03:00

A short tip today.

When you delete files and directories in Emacs 23 (say, with dired), instead of losing the files until the end of times (or at least until the singularity), you can move them to the 'trashcan', by whatever name that rose comes in your system, 'Trash' or 'Recycle Bin'…

To enable this, put the following in your .emacs:

(setq delete-by-moving-to-trash t)

There is one problem - a bug? I am using Ubuntu 9.04, which follows the Freedesktop Trash Spec; it moves delete file in ~/.local/share/Trash, together with some metadata, so it can restore the file to their original location. However, emacs follows some older convention, ie. to move the file to ~/.Trash, and without any metadata.

You can partially fix this by making ~/.Trash a symlink to ~/.local/share/Trash/files/, but of course that does not get you the metadata.