GNU bug report logs - #71370
30.0.50; Please un-obsolete buffer-substring as a generalized variable

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From: Adam Porter <adam <at> alphapapa.net>
To: Michael Heerdegen <michael_heerdegen <at> web.de>
Cc: 71370 <at> debbugs.gnu.org
Subject: bug#71370: 30.0.50; Please un-obsolete buffer-substring as a generalized variable
Date: Thu, 27 Jun 2024 10:09:39 -0500

Hi Michael,

On 6/19/24 18:44, Michael Heerdegen wrote:
> Adam Porter <adam <at> alphapapa.net> writes:
> 
>> ┌────
>> │ (let ((inhibit-read-only t))
>> │   (setf (buffer-substring (oref (magit-current-section) start)
>> │                           (oref (magit-current-section) end))
>> │         "foobar\n"))
>> └────
>>
>> Otherwise, one would have to use `delete-region' and then `insert',
>> which is more cumbersome and error-prone.
> 
> I guess alternatively you could define a helper function and make that
> `setf'able, like
> 
> #+begin_src emacs-lisp
> (defalias 'magit-buffer-substring #'buffer-substring)
> (gv-define-simple-setter magit-buffer-substring
>                           cl--set-buffer-substring)
> #+end_src

One could, but it would seem tedious and wasteful to have do that across 
tens or hundreds of Elisp packages that use this setter and have for years.

The minor ambiguities you point out in one of your later messages are 
fair to note; however, they aren't new, and they don't appear to have 
discouraged use of this form in practice.  On the contrary, the form 
appears to be widely useful and understood easily enough.

Given that Emacs is full of idiosyncrasies which are much more impactful 
and challenging to understand, I'd think that it would be sufficient to 
document this one in the Elisp manual, like others are.  I'd certainly 
rather do that than deprive users of this useful, simple idiom which is 
already widely used.

--Adam

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