• help :command-completion
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• python.vim - A set of menus/shortcuts to work with Python files

Use the following when defining the command to enable completion.

-complete=customlist,{func} custom completion, defined via {func}

The {func} part should be a function with the following signature:

:function {func}(ArgLead, CmdLine, CursorPos)

The function should return the completion candidates as a Vim List. Non-string items in the list are ignored. Vim will not filter the returned completion candidates.

The following example completes filenames from the directories specified in the 'path' option:

command -nargs=1 -bang -complete=customlist,EditFileComplete
       \ EditFile edit<bang> <args>
function EditFileComplete(A,L,P)
    return split(globpath(&path, a:ArgLead), "\n")
endfunction

The function is called in two different ways:

• First the function is called to find the start of the text to be completed.
• Later the function is called to actually find the matches.

On the first invocation the arguments are:

a:findstart  1
a:base      empty

• The function must return the column where the completion starts. It must be a number between zero and the cursor column "col('.')".
• The text between this column and the cursor column will be replaced with the matches.
• Return -1 if no completion can be done.

a:findstart  0
a:base      the text with which matches should match; the text that was
            located in the first call (can be empty)

• The function must return a List of complete-items.
  • These matches usually include the "a:base" text.
• When there are no matches return an empty List.

Each list item can either be a string or a Dictionary. When it is a string it is used as the completion. When it is a Dictionary it can contain these items:

The "kind" item uses a single letter to indicate the kind of completion. This may be used to show the completion differently (different color or icon). Currently these types can be used:

• When searching for matches takes some time call |complete_add()| to add each match to the total list. These matches should then not appear in the returned list!
• Call |complete_check()| now and then to allow the user to press a key while still searching for matches. Stop searching when it returns non-zero.

An example that completes the names of the months:

fun! CompleteMonths(findstart, base)
  if a:findstart
    " locate the start of the word
    let line = getline('.')
    let start = col('.') - 1
    while start > 0 && line[start - 1] =~ '\a'
      let start -= 1
    endwhile
    return start
  else
    " find months matching with "a:base"
    let res = []
    for m in split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec")
      if m =~ '^' . a:base
    call add(res, m)
      endif
    endfor
    return res
  endif
endfun
set completefunc=CompleteMonths

The same, but now pretending searching for matches is slow:

fun! CompleteMonths(findstart, base)
  if a:findstart
    " locate the start of the word
    let line = getline('.')
    let start = col('.') - 1
    while start > 0 && line[start - 1] =~ '\a'
      let start -= 1
    endwhile
    return start
  else
    " find months matching with "a:base"
    for m in split("Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec")
      if m =~ '^' . a:base
    call complete_add(m)
      endif
      sleep 300m    " simulate searching for next match
      if complete_check()
    break
      endif
    endfor
    return []
  endif
endfun
set completefunc=CompleteMonths