Ggtcf

I want to be able to write bit and have it expand to something in vim. How do I encode a backslash in the left-hand side of an abbreviation, though?

I tried all of these:

:iab bit replacement_text
:iab <Bslash>bit replacement_text
:iab <bs>bit replacement_text

but got E474: Invalid argument for all of these.

The map_backslash help-topic suggests <Bslash>, but this doesn't seem to work.

You can define your abbreviation on "bit", and then test if it is preceded by "", if so, return the new text, or "bit" otherwise.

function! s:Expr(default, repl)
 if getline('.')[col('.')-2]==''
 return "<bs>".a:repl
 else
 return a:default
 endif
endfunction

:inoreab bit <c-r>=<sid>Expr('bit', 'foobar')<cr>

That's the kind of tricks I used in MapNoContext().

EDIT: see :h abbreviations for the reasons why what you asked can't be achieved directly.

EDIT2: It can be easily encapsulated this way:

function! s:DefIab(nore, ...)
 let opt = ''
 let i = 0
 while i != len(a:000)
 let arg = a:000[i]
 if arg !~? '<buffer>|<silent>'
 break
 endif
 let opt .= ' '.arg
 let i += 1
 endwhile

 if i+2 != len(a:000)
 throw "Invalid number of arguments"
 endif
 let lhs = a:000[i]
 let rhs = a:000[i+1]

 exe 'i'.a:nore.'ab'.opt.' '.lhs.' <c-r>=<sid>Expr('.string(lhs).', '.string(rhs).')<cr>'
endfunction

command! -nargs=+ InoreabBSlash call s:DefIab('nore', <f-args>)

And used with a simple:

InoreabBSlash <buffer> locbit foobar

or

InoreabBSlash bit foobar

I suggest using backslash on both sides, vim is happy that way:

inoreabbr bit replacement_text

Note that I am using the "nore" version of abbr, better to be clear if you don't intend a recursive expansion. I have been using the below abbreviations for a long time and they work great:

inoreabbr time <C-R>=strftime("%d-%b-%Y @ %H:%M")<CR>
inoreabbr date <C-R>=strftime("%d-%b-%Y")<CR>

you could

 inoremap bit replacementtext

Also if you dont like the lag an alternative leader like backtick ` (above the tab for me)

 :iab `f foobar

if you are not using them in your code often

You can only use a backslash as a prefix for an abbreviation if it's only got a single character following it, so :iab b replacementtext will work.

:set iskeyword+=

in vimrc_tex (or just vimrc) works perfectly.