From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Eli Zaretskii <eliz@gnu.org>
Cc: Alan Mackenzie <acm@muc.de>, emacs-devel@gnu.org
Subject: Re: Edebug corrupting point in buffers; we need buffer-point and set-buffer-point, perhaps.
Date: Mon, 31 Oct 2022 13:19:34 -0400 [thread overview]
Message-ID: <jwva65b6hoz.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <83pme8dp2r.fsf@gnu.org> (Eli Zaretskii's message of "Mon, 31 Oct 2022 16:50:52 +0200")
>> Anyhow, I proposed buffer-point and set-buffer-point. They would be a
>> lot faster than set-buffer followed by point and goto-char. Here is my
>> first version of these. What do you think?
>
> I'm not sure performance in a debugger is a reason good enough to add
> 2 more primitives. The fact that we didn't need them until now should
> tell us something, no?
> Stefan, Lars, WDYT?
I'd be interested to see numbers showing that it's indeed "too costly"
to just use `set-buffer`, before we add such primitives.
> Anyway, a couple of minor comments:
AFAIK `get-buffer` will return non-nil when passed a killed buffer, so
I think those two functions currently would misbehave when passed
a killed buffer.
>> +DEFUN ("buffer-point", Fbuffer_point, Sbuffer_point, 1, 1, 0,
>> + doc: /* Return the buffer point of BUFFER-OR-NAME.
>> +The argument may be a buffer or the name of an existing buffer. */)
>> + (Lisp_Object buffer_or_name)
>
> Why not an optional argument to 'point'?
That would be a lot more invasive, so hard to justify for
a functionality that we're not even sure we want to have.
> And why in buffer.c and not in editfns.c?
[ Truth be told, I don't really understand how these are split :-( ]
>> + CHECK_FIXNUM_COERCE_MARKER (pos);
>> + p = XFIXNUM (pos);
>
> This is sub-optimal: a marker holds both character and byte position,
> and you lose it here. Ignoring the byte position is only justified if
> the marker belongs to the wrong buffer.
I suspect the performance impact is negligible compared to what it would
cost using `set-buffer`. Since we're not convinced the cost of
`set-buffer` is high enough to justify `set-buffer-point`, I wouldn't
worry about optimizing the case where the arg is a marker.
Stefan
next prev parent reply other threads:[~2022-10-31 17:19 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-31 11:43 Edebug corrupting point in buffers; we need buffer-point and set-buffer-point, perhaps Alan Mackenzie
2022-10-31 13:16 ` Eli Zaretskii
2022-10-31 14:32 ` Alan Mackenzie
2022-10-31 14:50 ` Eli Zaretskii
2022-10-31 15:46 ` Alan Mackenzie
2022-10-31 17:33 ` Stefan Monnier
2022-10-31 17:55 ` Eli Zaretskii
2022-10-31 20:46 ` Alan Mackenzie
2022-11-01 6:21 ` Eli Zaretskii
2022-10-31 17:19 ` Stefan Monnier [this message]
2022-10-31 18:09 ` Eli Zaretskii
2022-10-31 20:35 ` Stefan Monnier
2022-10-31 17:21 ` Stefan Monnier
2022-10-31 18:10 ` Eli Zaretskii
2022-10-31 23:14 ` Stefan Monnier
2022-11-01 7:06 ` Eli Zaretskii
2022-10-31 21:25 ` Alan Mackenzie
2022-11-01 6:45 ` Eli Zaretskii
2022-11-01 11:41 ` Edebug corrupting point in buffers Alan Mackenzie
2022-11-01 11:53 ` Eli Zaretskii
2022-11-01 13:42 ` Alan Mackenzie
2022-11-01 14:42 ` Eli Zaretskii
2022-11-01 17:06 ` Alan Mackenzie
2022-11-01 17:12 ` Eli Zaretskii
2022-11-01 17:24 ` Alan Mackenzie
2022-11-01 17:57 ` Eli Zaretskii
2022-11-01 19:02 ` Alan Mackenzie
2022-11-01 19:47 ` Stefan Monnier
2022-11-01 20:53 ` Alan Mackenzie
2022-11-01 21:51 ` Stefan Monnier
2022-11-02 10:40 ` Alan Mackenzie
2022-11-02 13:12 ` Stefan Monnier
2022-11-02 13:28 ` Eli Zaretskii
2022-11-02 3:28 ` Eli Zaretskii
2022-11-02 12:53 ` Stefan Monnier
2022-11-02 17:40 ` Juri Linkov
2022-11-02 18:26 ` Eli Zaretskii
2022-11-02 18:36 ` Juri Linkov
2022-11-02 18:52 ` Eli Zaretskii
2022-11-03 17:25 ` Juri Linkov
2022-11-03 18:06 ` Eli Zaretskii
2022-11-03 18:31 ` Juri Linkov
2022-11-02 11:34 ` Alan Mackenzie
2022-11-02 14:00 ` Eli Zaretskii
2022-11-02 16:18 ` Alan Mackenzie
2022-11-02 16:57 ` Eli Zaretskii
2022-11-03 11:32 ` Alan Mackenzie
2022-11-03 13:29 ` Eli Zaretskii
2022-11-03 18:07 ` Alan Mackenzie
2022-11-03 18:15 ` Eli Zaretskii
2022-11-03 20:25 ` Alan Mackenzie
2022-11-05 11:24 ` Eli Zaretskii
2022-11-05 16:50 ` Alan Mackenzie
2022-11-06 8:10 ` Eli Zaretskii
2022-11-06 14:40 ` Alan Mackenzie
2022-11-03 19:29 ` Stefan Monnier
2022-11-03 19:36 ` Eli Zaretskii
2022-11-03 20:39 ` Stefan Monnier
2022-11-04 6:34 ` Eli Zaretskii
2022-11-04 6:37 ` Eli Zaretskii
2022-11-03 19:57 ` Alan Mackenzie
2022-11-03 20:35 ` Stefan Monnier
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