bug#71370: 30.0.50; Please un-obsolete buffer-substring as a generalized variable

[Adam Porter <adam@alphapapa.net>]

Hi,

Continuing with the theme of requesting the unobsoleting of some
generalized variable forms (see [#65555] and [earlier discussion]), and
given Eli's recently [mentioning] the upcoming cut of the Emacs 30
release branch, I'd like to request now that `buffer-substring' be
unmarked as obsolete.

This form makes some operations much more concise than they would
otherwise be.  For example, if one wants to update the text in a
`magit-section' section, the code could be as simple as this:

┌────
│ (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.

As well, code exists in the wild which uses this form: for example,
[pcre2el], a very useful library which I use in `magit-todos' to convert
regexp between Elisp and Perl-styles.

Overall, it's a useful paradigm that makes code more readable and
concise, and I'm not aware of any drawbacks to using it; if there are
any, I think they should be discussed publicly before marking the form
as obsolete.

As I've mentioned in earlier discussions, the mass-marking of several GV
forms as obsolete in commit 48aacbf292fbe8d4be7761f83bf87de93497df27
happened apparently without public discussion, as well as without
checking the extent to which they are used outside of emacs.git.

By the way, I'd also like to request that the `point' and `window-point'
GV forms be unobsoleted, for the same reasons.  If it's permissible, I'd
like to do so here rather than file separate bug reports for each of
those, but if the maintainers prefer, I will do so.

Thanks for your consideration, and your work on Emacs.

–Adam


[#65555] <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=65555>

[earlier discussion]
<https://lists.gnu.org/archive/html/emacs-devel/2022-11/msg01408.html>

[mentioning]
<https://lists.gnu.org/archive/html/emacs-devel/2024-06/msg00042.html>

[pcre2el]
<https://github.com/joddie/pcre2el/blob/380723b2701cceb75c266440fb8db918f3340d50/pcre2el.el#L663>