automatic pairing of brackets and quotes

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.