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bug#21747: 25.0.50; while-no-input breaks kbd event handling when called
From: |
Artur Malabarba |
Subject: |
bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook |
Date: |
Sun, 25 Oct 2015 14:43:06 +0000 |
2015-10-24 11:52 GMT+01:00 Eli Zaretskii <eliz@gnu.org>:
>> Date: Sat, 24 Oct 2015 11:30:42 +0100
>> From: Artur Malabarba <bruce.connor.am@gmail.com>
>> Cc: Stefan Monnier <monnier@iro.umontreal.ca>, Kim Storm <storm@cua.dk>,
>> 21747@debbugs.gnu.org,
>> Eli Zaretskii <eliz@gnu.org>
>>
>> So maybe the docstring for post-command-hook should point out this detail and
>> recommend that functions added to this hook call sit-for if they're going to
>> do
>> potentially expensive processing.
>
> Just being potentially expensive is not enough to trigger the problem.
> You need to actually hog Emacs (or close to that) to prevent redisplay
> from eventually happening.
>
> I agree that expensive processing in post-command-hook is not a good
> idea (and said so several times in the past), but people are still
> doing that, so I guess just advertising the problem is not enough. (I
> don't object to adding this to documentation, of course.)
I've extended the docstring.
I used redisplay instead of (sit-for 0), because inside a call to
while-no-input it has the exact same effect and is more expressive.
Suggestions welcome.
-otherwise the error might happen repeatedly and make Emacs nonfunctional. */);
+otherwise the error might happen repeatedly and make Emacs nonfunctional.
+
+It is usually a bad idea to use this hook for expensive processing.
+If unavoidable, `while-no-input' can be used avoid making Emacs
+unresponsive while the user types. Furthermore, this hook is run
+before redisplay, so the effect of the executed command won't be
+displayed on the buffer until after the hook has finished (giving the
+impression that Emacs is hanging). You can call `redisplay' inside
+`while-no-input' to avoid this.
+
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, (continued)
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/24
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Stefan Monnier, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/26
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/24
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook,
Artur Malabarba <=
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Artur Malabarba, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/25
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Tassilo Horn, 2015/10/26
- bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook, Eli Zaretskii, 2015/10/24