Re: /srv/bzr/emacs/elpa r395: * company.el (company-capf): Add support for `sorted' and `post-completion'.

[Dmitry Gutov <dgutov@yandex.ru>]

Hi Stefan,

> ------------------------------------------------------------
> revno: 395
> committer: Stefan Monnier <monnier-CRDzTM1onBSWkKpYnGOUKg@public.gmane.org>
> branch nick: elpa
> timestamp: Sat 2013-04-27 09:48:47 -0400
> message:

>  ;; (defun company-my-backend (command &optional arg &rest ignored)
> -;;   (case command
> -;;     (prefix (when (looking-back "foo\\>")
> +;;   (pcase command
> +;;     (`prefix (when (looking-back "foo\\>")
>  ;;               (match-string 0)))
> -;;     (candidates (list "foobar" "foobaz" "foobarbaz"))
> -;;     (meta (format "This value is named %s" arg))))
> +;;     (`candidates (list "foobar" "foobaz" "foobarbaz"))
> +;;     (`meta (format "This value is named %s" arg))))

Like the header in company.el says, we still try to support Emacs 22 and
23. `pcase' was only added in 23.3, I believe.

> +(defun company-capf (command &optional arg &rest _args)
...
> +    (duplicates nil) ;Don't bother.
> +    (no-cache t)     ;FIXME: Improve!
> +    (meta nil)       ;FIXME: Return one-line docstring for `arg'.
> +    (doc-buffer nil) ;FIXME: Return help buffer for `arg'.
> +    (location nil)   ;FIXME: Return (BUF . POS) or (FILE . LINENB) of
> `arg'.
> +    (init nil)      ;Don't bother: plenty of other ways to initialize
> the code.

a) There's no need to return nils explicitly, other backends don't.

b) Who are these FIXMEs for? I guess `meta' can be implemented by
calling `:annotation-function' (don't know if it's appropriate), but
`doc-buffer' and `location' don't have anything corresponding in
`completion-extra-properties'.

> +    (require-match nil)            ;This should be a property of the
> front-end!

Should it really? A smart back-end could determine if we're typing a
function call, or typing the name for a new function, and at least
override it to `never' in the latter case.

Returning `t' might indeed never be appropriate for a back-end, and some
front-ends could want to have a say in this, but I'd rather see them in
practice first.

> +(defvar company-backend)
> +

This variable is declared about ~30 lines below that. Is it appropriate
to have both declarations in the same file?

>  Example:
>  \(company-begin-with '\(\"foo\" \"foobar\" \"foobarbaz\"\)\)"
> +  ;; FIXME: Shouldn't `company-begin-with-marker' be removed and replaced
> +  ;; by a lexical variable?

It probably should, but, again, lexical-binding is not available in
Emacs < 24. ATM I'm only using it to improve some logic that uses
`boundp' in `company-elisp'.