Different word boundaries in command mode

Question

I very commonly use CTRL-W to adjust a previous path in the command line, like I'll bring up the directory of the current file or perhaps a previous :e ... command from history that's close, and use CTRL-W to remove the filename and maybe a path segment or two before just typing the new suffix.

One of the annoyances of this is that removing, say, the "foo-bar.baz" filename at the end of the path requires hitting CTRL-W three times, and that particular chord is a little cumbersome.

So I was wondering if I could adjust the word boundaries to include '.' and '-' as word characters, but only in command mode.

Answer 1

I think I got something working (rewrote completely my original answer). It's another usecase of ++once autocmd.

function! FlashIskWith(what)
    let s:saved_isk = &iskeyword
    autocmd CmdlineChanged ++once exe "set isk=" . s:saved_isk
    exe "set iskeyword+=" . a:what
endfunction
function! C_W_WithIsk(what)
    call FlashIskWith(a:what)
    return "\<C-W>"
endfunction
cnoremap <expr> <C-W> C_W_WithIsk("-,.")

Now, pressing <C-W> in command-line mode will :

• save current &iskeyword
• load an autocmd to restore it whenever CmdlineChanged
• add - and . to &iskeyword
• "execute" <C-W> (see :h :map-expression)
• since it deletes the previous word, CmdlineChanged is triggered and &isk is restored.