bug#23852: 25.0.95; lazy-completion-table discards metadata

bug#23852: 25.0.95; lazy-completion-table discards metadata

[Michael Heerdegen]

Hello,

for example:

(completing-read
 "Input: "
 (letrec ((table (lazy-completion-table
                  table (lambda () (let ((cands '("1" "2")))
                                (lambda (string pred action)
                                  (if (eq action 'metadata)
                                      `(metadata
                                        (annotation-function . ,(lambda (_) " ---")))
                                    (complete-with-action
                                     action cands string pred))))))))
   table))


No annotations.

AFAICT this happens because lazy-completion-table is based on
completion-table-dynamic whose current implementation always returns
tables returning nil metadata.

There are workarounds, but it would be nicer if it just worked that
way...when the candidates are computed dynamically, an
annotation-function will ideally be computed along with them.


TIA,

Michael.



In GNU Emacs 25.0.95.1 (x86_64-pc-linux-gnu, GTK+ Version 3.20.6)
 of 2016-06-21 built on drachen
Repository revision: 6cdd8f7153b553c6dc02be47e04a2e75117b6fe4
Windowing system distributor 'The X.Org Foundation', version 11.0.11803000
System Description:	Debian GNU/Linux testing (stretch)

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GSETTINGS NOTIFY
LIBXML2 FREETYPE XFT ZLIB TOOLKIT_SCROLL_BARS GTK3 X11

bug#23852: 25.0.95; lazy-completion-table discards metadata

[Noam Postavsky]

On Sun, Jun 26, 2016 at 10:21 PM, Michael Heerdegen
<michael_heerdegen@web.de> wrote:
> for example:
>
> (completing-read
>  "Input: "
>  (letrec ((table (lazy-completion-table
>                   table (lambda () (let ((cands '("1" "2")))
>                                 (lambda (string pred action)
>                                   (if (eq action 'metadata)
>                                       `(metadata
>                                         (annotation-function . ,(lambda (_) " ---")))
>                                     (complete-with-action
>                                      action cands string pred))))))))
>    table))

When trying to evaluate this, I get an error after hitting TAB at the prompt:

Debugger entered--Lisp error: (void-variable table)
  (functionp table)
  (if (functionp table) (progn (setq table (funcall (function (lambda
nil (let (...) (function ...))))))))
[...]

bug#23852: 25.0.95; lazy-completion-table discards metadata

[Michael Heerdegen]

Noam Postavsky <npostavs@users.sourceforge.net> writes:

> When trying to evaluate this, I get an error after hitting TAB at the prompt:
>
> Debugger entered--Lisp error: (void-variable table)

Sorry, forgot to mention: you need to evaluate with lexical-binding
non-nil.


Michael.