Vim: recursive iabbrev

TLDR: Although Vim documentation says “Abbreviations are never recursive,” you can get abbreviations to recurse by escaping to the command mode.

* * *

When I write specs there is usually a little bit of boilerplate, for example:

describe('some feature', function() {
    // tests go here
});

then there are a few similar calls for setup, teardown, and individual tests, and each of them contains a function expression. And then there are also quite frequent cases when I need a function expression as a callback, IIFE, or an iteratee for FP-style chains with map and friends.

Although it can get into muscle memory with time, it’s still a lot of typing, and to avoid that I have set up a few iabbrevs, for example:

iabbrev tede describe(', function() {});<esc>F}i<cr><esc>O<tab><up><esc>2f'i

this lets me type tede and when I press <space> I get this:

describe(', function() {

});

and the cursor is placed between the quotes in insert mode, so I can just type the feature description. Neat! 8-)

I will reformat for readability like this:

iabbrev tede describe(', function() {});
  \<esc>F}i<cr>
  \<esc>O<tab><up>
  \<esc>2f'i

Now, at my day job, the code convention says that in function expressions we have to have a space before the opening paren. Um… OK: I have set exrc in my ~/.vimrc, so I can just have a per-project .vimrc that would redefine those iabbrevs, with the space before the opening paren. OK.

Then a few weeks ago I’ve played a bit with Calypso and their coding guidelines ask for a space before the opening paren, but also on the inside of parens, similar to jQuery’s.

The thought of having yet another .vimrc with all the iabbrevs didn’t sound right, and knowing that the only difference was the spacing around parens in function expressions, I thought: I should be able to somehow extract the iabbrev for function expression, and only have that redefined on a per-project basis.

Googled a bit, and then found a StackOverflow answer mentioning that Vim’d docs explicitly say:

Abbreviations are never recursive.

Um… OK. But I know that in software Everything is possible®, so I went and re-read the docs section on abbreviations from cover to cover. Nothing.

Then I realized that I can escape to normal mode in the abbreviation body by pressing <Esc> and from there I can run a command-line mode command, and from there I can execute a :normal command that can execute another iabbrev:

 iabbrev xx <esc>:normal a_some_iabbrev<cr>

So,

<Esc> switches to normal mode;
: switches to command-line mode;
normal command-line command executes the given normal command, which in this case is a_some_iabbrev which reads as: enter insert mode, and type in _some_iabbrev;
<CR> at the end is as we’d press to execute the command after we entered it in the command line.

OK, so now if I have the function expression in a (conventionally) private abbrev like this:

iabbrev _fn function() {}

I can redefine my earlier tede iabbrev like this:

iabbrev tede <esc>:normal a_fn<cr>
  \Idescribe(',<space>
  \<esc>A);
  \<esc>F}i<cr>
  \<esc>O<tab><up>
  \<esc>f'a

which, first runs _fn (which expands to function() {}), then types in the other pieces around it, just as before.

Now, for the projects at work I only need to redefine _fn to have the space before the paren:

iabbrev _fn function () {}

Neat! 8-)

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If you get into an infinite loop, Vim errors out when stack size is 200. For example, here _ia3 calls _ia2, which calls _ia1, which closes the loop calling _ia3:

iabbrev _ia1 ia1<esc>:normal a_ia2<cr>a
iabbrev _ia2 ia2<esc>:normal a_ia3<cr>a
iabbrev _ia3 ia3<esc>:normal a_ia1<cr>a

If you try to run any of these, you’ll get 200 of ia[123] typed into your buffer, after which Vim will stop and throw an error:

Error detected while processing InsertEnter Auto commands for "*":

So you can’t get too far down the wrong path. :-)

* * *

It would be really awesome to hear your thoughts on this solution. Thank you! :)

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