VIM: Calling a function from insert mode with imap?

Question

I have a function that I've written in my vimrc to turn syntax off and set paste. The function looks like this:

function! ToggleSyntax()
if g:syntaxon == 1
syntax off
set paste
let g:syntaxon = 0
else
syntax on
set nopaste
let g:syntaxon = 1
endif
endfunction

I use the F12 key to call the function, and have mapped the function to F12 like this:

map <F12> :call ToggleSyntax()<cr>
imap <F12> <c-o>:call ToggleSyntax()<cr>

the problem that I'm having is that I can't call the ToggleSyntax function from insert mode. This is very confusing to me, because I have used the imap handler, but still, this function only works from command mode. I can't figure out how to get it to work, any help with this would be greatly appreciated! thank you!

Answer 1

For me, your function also turns paste on in insert mode, but it doesn't turn it back off (and syntax on). The reason is that when :set paste, no insert mode mappings apply. That's one essential aspect of 'paste', see also :help 'paste'.

The only way to toggle in insert mode is

:set pastetoggle=<F12>

(that option was explicitly made for this purpose) but then, you'll lose the parallel syntax toggling that your function provides.