From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Eli Zaretskii <eliz@gnu.org>
Cc: michael_heerdegen@web.de, radon.neon@gmail.com, 31692@debbugs.gnu.org
Subject: bug#31692: Emacs sometimes drops key events
Date: Thu, 07 Jun 2018 14:44:36 -0400 [thread overview]
Message-ID: <jwvo9gmla1v.fsf-monnier+emacsbugs@gnu.org> (raw)
In-Reply-To: <83602uwq3y.fsf@gnu.org> (Eli Zaretskii's message of "Thu, 07 Jun 2018 18:52:49 +0300")
>> I don't understand the (throw 'throw-on-input t)
>> (throw throw-on-input t) would make more sense, but in any case we're
>> just about to exit that `catch` so throwing won't have any real effect.
> I hoped the comment explained that, but evidently not.
I think I understood the comment (and the email message before that ;-),
and your analysis makes a lot of sense, but AFAICT the "normal" way this
special quit-flag value is handled in the C code (see process_quit_flag
in src/eval.c) is to
- read quit-flag
- notice it's `eq`ual to the value of throw-on-input
- set quit-flag to nil
- throw to the flag's value
so the throw is not done to the constant symbol `throw-on-input` but to
the value of this variable, and the magic doesn't happen in response to
this throw (i.e. it's not done within the implementation of the
throw/catch code), but instead it happens before the throw.
As a consequence, instead of
(throw 'throw-on-input t)
we need to throw like
(throw throw-on-input t)
and we additionally need to (setq quit-flag nil) before that.
>> I think instead of (throw 'throw-on-input t) what is needed here is
>>
>> (setq quit-flag nil)
>>
>> which will also make the body return nil (rather than t like (throw
>> throw-on-input t) would), which I believe is also the right thing.
>
> I believe we need to return t here, because input did arrive.
Indeed, I had missed that
So I suggest
(progn (setq quit-flag nil) t)
We could also use (throw throw-on-input t) after the setq, but I don't
see the point since it seems it would give exactly the same result just
in a more costly way.
Stefan
next prev parent reply other threads:[~2018-06-07 18:44 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-03 2:21 bug#31692: Emacs sometimes drops key events Radon Rosborough
2018-06-03 2:36 ` Eli Zaretskii
2018-06-03 4:54 ` Radon Rosborough
2018-06-03 15:05 ` Eli Zaretskii
2018-06-03 19:23 ` Alan Third
2018-06-04 10:41 ` João Távora
2018-06-05 0:59 ` Michael Heerdegen
2018-06-05 2:37 ` Eli Zaretskii
2018-06-05 2:41 ` Radon Rosborough
2018-06-05 4:11 ` Eli Zaretskii
2018-06-05 21:40 ` Michael Heerdegen
2018-06-06 2:37 ` Eli Zaretskii
2018-06-06 2:58 ` Michael Heerdegen
2018-06-06 14:52 ` Eli Zaretskii
2018-06-06 23:12 ` Michael Heerdegen
2018-06-07 15:20 ` Eli Zaretskii
2018-06-06 14:45 ` Eli Zaretskii
2018-06-06 22:50 ` Michael Heerdegen
2018-06-07 15:20 ` Eli Zaretskii
2018-06-07 15:30 ` Stefan Monnier
2018-06-07 15:52 ` Eli Zaretskii
2018-06-07 18:44 ` Stefan Monnier [this message]
2018-06-08 22:17 ` Michael Heerdegen
2018-06-11 21:08 ` Michael Heerdegen
2018-06-12 2:27 ` Eli Zaretskii
2018-06-16 8:26 ` Eli Zaretskii
2018-06-16 8:28 ` Eli Zaretskii
2018-06-17 4:39 ` Michael Heerdegen
2018-07-05 19:07 ` Michael Heerdegen
2018-07-05 19:27 ` Eli Zaretskii
2018-07-06 17:43 ` Michael Heerdegen
2018-06-05 2:48 ` Michael Heerdegen
2018-06-05 4:13 ` Eli Zaretskii
2018-06-05 11:57 ` Noam Postavsky
2018-06-05 14:31 ` Eli Zaretskii
2018-06-05 21:39 ` Artur Malabarba
2018-06-06 14:39 ` Eli Zaretskii
2018-06-03 12:13 ` Noam Postavsky
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