Re: completion-ui.el question: my vimpulse-show-completion-menu function always gives me an empty menu

[Toby Cubitt]

Hi,

I'm not surprised it doesn't work, because you're using completion-UI in 
completely the wrong way. (Excusable, since documentation is currently 
fairly non-existent :-) Instead, set 'completion-function' to a function 
that returns a list of possible completions, and leave completion-UI to 
do its job.

Your comment 2. is along the right lines: menu completion shouldn't be 
implemented in the vimpulse code base, or indeed in the code base of any 
other completion package. It should indeed be in something like the 
hippie-expand package. But that's precisely what completion-UI is! All 
the hippie-expand features, plus tooltips, menu-completion, 
auto-completion, hotkey completion etc. etc. Completion-UI is supposed 
to supersede hippie-expand, at least for in-buffer completion. So using 
completion-UI and hippie-expand at the same time is unlikely to work 
very well.

As an Elisp coder, you're not supposed to invoke *any* completion 
interface explicitly, as you've tried to do. Deciding which combination 
of user-interfaces to use is the user's business, not the package 
writer's. Maybe some users want to use menu completion, but others 
prefer to see a list in the echo area, whilst still others just want a 
tooltip to popup after a delay, etc. etc. Completion-UI offloads those 
choices onto the user, which is where they should be.

I hope that makes things a bit clearer. I fully appreciate that using 
completion-UI will be confusing until it's properly documented, although 
the commentary at the beginning of completion-ui.el does tersely explain 
how it should be used. (Setting 'completion-function' really is all 
there is to it, I promise!)

Toby


Jason Spiro wrote:
> Hi all,
>
> I am trying to get menu completion working for Alessandro Piras'
> vimpulse.el, available on EmacsWiki.  (Menu completion is an
> ultra-nice feature.  Instead of having to press M-/ over and over
> until you get what you want, you get a drop-down menu listing the
> completion options.  To see what menu completion looks like in Vim,
> see 
> http://en.wikibooks.org/wiki/Learning_the_vi_editor/Vim/Useful_things_for_programmers_to_know) 
>
>
> If you have Toby Cubitt's predictive completion from
> http://www.dr-qubit.org/emacs.php installed (incidentally, it's a very
> cool package), I would appreciate if you could run this code so you
> can answer my question 1 below:
>
> ;; Begin code {{{
>
> (require 'completion-ui)
>
> ;; Note: This code has an additional bug in addition to the problem I
> ;; am asking about in this mailing list message:
> ;; When called with a MAXNUM of nil, this func sometimes fails.  (Seems
> ;; to work the first time, then fail all times after, in such cases.
> ;; To fix, call with a normal MAXNUM.)
> (defun vimpulse-try-hippie-expand-listed-functions (prefix &optional 
> maxnum)
> ;  (interactive "*MString to expand:
> ;nMaximum number of expansions, or nil for unlimited: ")
>  (setq expansions nil)
>  (with-temp-buffer
>    (insert-string prefix)
>    (hippie-expand nil)
>    (unless (string-equal (current-message) "No expansion found")
>      (while (and
>              (not (string-equal
>                    (current-message)
>                    "No further expansions found"))
>              (if maxnum (not (= (length expansions) maxnum))))
>        ;; Hippie-expand was designed to be run interactively.  If
>        ;; this-command and last-command are equal, it assumes it's
>        ;; being called as a "repeated use" (additional call without
>        ;; moving the point) and searches for additional expansions
>        ;; with the same prefix.  So, make this-command and
>        ;; last-command equal.
>        (setq this-command last-command)
>        (hippie-expand nil)
>        (add-to-list 'expansions (buffer-string))
>        (buffer-string)
>      ))
>    expansions))
>
> (defun vimpulse-show-completion-menu ()
>  (interactive)
>  (setq-default completion-function
> 'vimpulse-try-hippie-expand-listed-functions)
>  (setq completion-function 'vimpulse-try-hippie-expand-listed-functions)
>  ;; is this always necessary?  Am I even ever supposed to call it?
>  (completion-setup-overlay 'prefix)
>  (completion-show-menu))
>
> ;; }}} End code
>
> 1. Whenever I start typing a word then run
> vimpulse-show-completion-menu I get an empty menu.  Why?  (Am I using
> completion-show-menu wrong?  It errors on me if I don't call
> completion-setup-overlay first, so I call it first.  Should I?  In
> general, what is the proper way to use completion-show-menu?  It's not
> perfectly documented.
>
> 2. Should menu completion really be part of vimpulse.el, or should I
> try to get it into the hippie-expand source base?  Or, alternatively,
> would someone like to take over maintainership of my attempt to get
> menu completion working in Emacs?
>
> Thanks in advance,
> Jason
>
> P.S. I am using GNU Emacs 22.0.50.1 (i486-pc-linux-gnu, GTK+ Version
> 2.10.3) of 2006-09-19 on rothera, modified by Debian.  That's 6 months
> old.  I am using predictive 0.16.2; I downloaded it today.