bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Drew Adams]

Subject line says it all.  Please do.

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2014-02-11 on ODIEONE
Bzr revision: 116410 lekktu@gmail.com-20140211204823-l9l2s6tktfitq266
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3' LDFLAGS=-Lc:/Devel/emacs/lib
 CPPFLAGS=-Ic:/Devel/emacs/include'

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Lars Ingebrigtsen]

Drew Adams <drew.adams@oracle.com> writes:

> Subject line says it all.  Please do.

Hm...  would that be completion over this?

(fontset-list)
=>
("-DAMA-Ubuntu Mono-normal-normal-normal-*-24-*-*-*-m-0-fontset-startup" "-*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard" "-*-*-*-*-*-*-*-*-*-*-*-*-fontset-default")

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Drew Adams]

> Hm...  would that be completion over this?
> 
> (fontset-list)
> =>
> ("-DAMA-Ubuntu Mono-normal-normal-normal-*-24-*-*-*-m-0-fontset-startup"
> "-*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard" "-*-*-*-*-*-*-
> *-*-*-*-*-*-fontset-default")

No.  That is a list of fontsets, not fonts.

The completion candidates should be the installed fonts.

This is what I use, FWIW:

(let ((fonts        (make-hash-table :test #'equal))
      (fontset-lst  (fontset-list)))
  (setq fontset-lst  (delete "-*-*-*-*-*-*-*-*-*-*-*-*-fontset-default"
                             fontset-lst))
  (dolist (ft  (append fontset-lst (x-list-fonts "*"))  fonts)
    (puthash ft t fonts)))

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Eli Zaretskii]

> Date: Fri, 29 Apr 2016 11:39:59 -0700 (PDT)
> From: Drew Adams <drew.adams@oracle.com>
> Cc: 16815@debbugs.gnu.org
> 
> This is what I use, FWIW:
> 
> (let ((fonts        (make-hash-table :test #'equal))
>       (fontset-lst  (fontset-list)))
>   (setq fontset-lst  (delete "-*-*-*-*-*-*-*-*-*-*-*-*-fontset-default"
>                              fontset-lst))
>   (dolist (ft  (append fontset-lst (x-list-fonts "*"))  fonts)
>     (puthash ft t fonts)))

IMO, this is madness: you are bloating the Emacs session with hundreds
of fonts, most of which Emacs will never need to use, or even know
about.  We certainly shouldn't do anything like that in Emacs.

The doc string of describe-font clearly says that the font must be one
which Emacs already loaded, so completing on all the _installed_ fonts
is definitely not TRT.

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> This is what I use, FWIW:
>> 
>> (let ((fonts        (make-hash-table :test #'equal))
>>       (fontset-lst  (fontset-list)))
>>   (setq fontset-lst  (delete "-*-*-*-*-*-*-*-*-*-*-*-*-fontset-default"
>>                              fontset-lst))
>>   (dolist (ft  (append fontset-lst (x-list-fonts "*"))  fonts)
>>     (puthash ft t fonts)))
>
> IMO, this is madness: you are bloating the Emacs session with hundreds
> of fonts, most of which Emacs will never need to use, or even know
> about.  We certainly shouldn't do anything like that in Emacs.
>
> The doc string of describe-font clearly says that the font must be one
> which Emacs already loaded, so completing on all the _installed_ fonts
> is definitely not TRT.

I'm not sure I understand the objection here.  The form suggested by
Drew just gets a list of font names -- it doesn't load anything, so it
should be harmless?

And the doc string of describe-font seems to be wrong.  You can ask it
to describe a font that's not loaded.  Or at least it seems that way
when I test it.  

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: Drew Adams <drew.adams@oracle.com>,  16815@debbugs.gnu.org
> Date: Sat, 02 Nov 2019 17:23:01 +0100
> 
> I'm not sure I understand the objection here.  The form suggested by
> Drew just gets a list of font names -- it doesn't load anything, so it
> should be harmless?

A list of many hundreds of long strings is not cheap.  However, ...

> And the doc string of describe-font seems to be wrong.  You can ask it
> to describe a font that's not loaded.  Or at least it seems that way
> when I test it.  

... yes, you are right, sorry.  So please also fix the doc string of
describe-font and the comments inside it, and also the doc string of
font-info, which it calls.

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

>> And the doc string of describe-font seems to be wrong.  You can ask it
>> to describe a font that's not loaded.  Or at least it seems that way
>> when I test it.  
>
> ... yes, you are right, sorry.  So please also fix the doc string of
> describe-font and the comments inside it, and also the doc string of
> font-info, which it calls.

OK; done.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#16815: 24.3.50; Provide completion for `describe-font' (enhancement request)

[Drew Adams]

> IMO, this is madness: you are bloating the Emacs session with hundreds
> of fonts, most of which Emacs will never need to use, or even know
> about.  We certainly shouldn't do anything like that in Emacs.

I don't think it is madness.  I (and others) have been taking
advantage of it for a long time.

> The doc string of describe-font clearly says that the font must be one
> which Emacs already loaded, so completing on all the _installed_ fonts
> is definitely not TRT.

I certainly wouldn't have a problem with that: completing against
the installed fonts is fine by me.  My reply to Lars was to make
the point that this is about choosing a font, not choosing a
fontset - completion should be against font names.

[Note: Things are a lot different if you can complete against
parts of the font name, and especially if you can do so
progressively, to narrow down the matching candidates.  If
all you have is a single pattern-match attempt then the
completion behavior is much less helpful/interesting.]