GNU bug report logs - #77942
31.0.50; replace-region-contents gets stuck

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Message #62 received at 77942 <at> debbugs.gnu.org (full text, mbox):

From: Gerd Möllmann <gerd.moellmann <at> gmail.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Paul Eggert <eggert <at> cs.ucla.edu>, 77942 <at> debbugs.gnu.org
Subject: Re: bug#77942: 31.0.50; replace-region-contents gets stuck
Date: Tue, 22 Apr 2025 15:33:10 +0200

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

> Gerd Möllmann [2025-04-22 05:48:14] wrote:
>> Stefan Monnier <monnier <at> iro.umontreal.ca> writes:
>>> Gerd, IIUC you're trying to use this to benchmark the charpos->bytepos
>>> code, in which case you should be better served by a call where the text
>>> and its replacement are of fairly similar size.
>>
>> That's right, it's for a bencnmark that helps me to get an impression if
>> avoiding the binary search in the charpos -> bytepos case is worth it.
>> Now that I know what replace-region-contents does, that's no problem.
>>
>> But honestly, what the heck? Does someone know what this diffing is
>> about in the first place? I mean, that replacing a region takes O(ND) is
>> not something that I would have thought possible. 
>
> That's why I wanted (well, still want) to have a `replace-region` that
> does just the plain/stupid/naive replacement, and then keep
> `replace-region-contents` as a separate function (ideally even renamed
> to something like `replace-region-slowly` or
> `replace-region-carefully`).

100% agreement. +ND

> One place where the diff's extra work is worthwhile is when you do
> reindent/prettyprint via an external process.

Thanks. 

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