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From: Alan Mackenzie <acm@muc.de>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: Making Emacs Lisp easier to debug
Date: Sat, 11 Nov 2023 12:10:33 +0000	[thread overview]
Message-ID: <ZU9vOQqlpf6-TQKE@ACM> (raw)
In-Reply-To: <83fs1cwnnv.fsf@gnu.org>

Hello, Eli.

On Sat, Nov 11, 2023 at 13:10:44 +0200, Eli Zaretskii wrote:
> > Date: Sat, 11 Nov 2023 11:04:01 +0000
> > Cc: emacs-devel@gnu.org
> > From: Alan Mackenzie <acm@muc.de>

> > :-)  I really meant has anybody looked into making redisplay reentrant.

> Good luck with that!

> (I also don't understand why you think this will help with font-lock,
> nor even how it would work in general, should it be possible.

With font lock, or any other Lisp hook called from redisplay, it should
be possible, in a recursive-edit loop, to run edebug, displaying on a
different frame.  That different frame would be running in the inner
redisplay while the outer redisplay would be suspended.

> Re-entering redisplay in the middle of a redisplay cycle means that
> the outer redisplay didn't finish preparing the glyph matrices, and
> what do you want the inner redisplay to do in such a case?

Work with the glyph matrices belonging to the inner redisplay whilst the
outer one is suspended.

> )

As I say, it is not clear whether or not this is possible or
practicable.  If it were, we could enhance edebug such that a function
in a font lock pattern, or on, say, window-scroll-functions could be
edebugged by doing nothing more than instrumenting it with C-u C-M-x.
Thus Lisp called from redisplay would cease to be an awkward special
case as far as debugging is concerned.

-- 
Alan Mackenzie (Nuremberg, Germany).



  reply	other threads:[~2023-11-11 12:10 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-10 20:56 Making Emacs Lisp easier to debug Alan Mackenzie
2023-11-11  6:52 ` Eli Zaretskii
2023-11-11  9:01   ` Ihor Radchenko
2023-11-11 11:04   ` Alan Mackenzie
2023-11-11 11:10     ` Eli Zaretskii
2023-11-11 12:10       ` Alan Mackenzie [this message]
2023-11-11 13:47         ` Eli Zaretskii
2023-11-11 14:56           ` Alan Mackenzie
2023-11-11 16:01             ` Eli Zaretskii
2023-11-11 17:23               ` Alan Mackenzie
2023-11-11 17:54                 ` Eli Zaretskii
2023-11-11 19:55                   ` Alan Mackenzie
2023-11-12  7:17                     ` Eli Zaretskii
2023-11-12 12:08                       ` Alan Mackenzie
2023-11-12 12:28                         ` Eli Zaretskii
2023-11-13 18:20                       ` XY Problems (tangent, related to common discussion issue here) chad

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