Vim Pre-Exit (Esc Key) Command?

Right now in开发者_开发问答 Vim when I go to a new line (or press 'p' or 'o' in normal mode) I get a lovely automatic indent, that also disappears if I exit insert mode without adding anything to it.

Is there a way to bind something to before I exit insert mode, such as inserting a phantom character then removing it?

Argh, I just read about this exact thing like two days ago but I can't remember where.

Anyway, the trick is to input a character right after <CR> and delete it immediately. There are a bunch of ways to do it:

<CR>a<Esc>x
<CR>a<C-w>
<CR>a<BS>

--EDIT--

Vim being Vim there are probably many other ways.

To automate these, you need to add a mapping to your .vimrc:

inoremap <CR> <CR>a<BS> " insert mode mapping for <CR>
nnoremap o oa<BS>       " normal mode mapping for o

But I'm not sure you should overwrite defaults like that.

--EDIT--

However, what is annoying with Vim's default behaviour is that you may need to do some <Tab><Tab><Tab><Tab> before actually inputing some text on non-indented line or do == when you are done or rely on the automatic indentation rules for your language at the next <CR>.

All that can be skipped by using <S-S> which puts you in INSERT mode right at the correct indentation level.

Try either cc or S in normal mode to change a line with respect to indention. No need for phantom characters.

:h cc
:h S

A mapping like the following should do the trick:

imap <esc> <esc>:s/\s\+$//<CR>

This one deletes trailing characters when you press esc in insert mode.