From: "Basil L. Contovounesios" <contovob@tcd.ie>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: master f51f963: Fix some side-effecting uses of make-text-button
Date: Fri, 05 Jun 2020 14:50:55 +0100 [thread overview]
Message-ID: <87v9k5mxj4.fsf@tcd.ie> (raw)
In-Reply-To: <jwvv9k5smqa.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Fri, 05 Jun 2020 09:02:54 -0400")
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> As Paul said, not quite - it has historically modified its first
>> argument by placing properties on it. If you look at the line preceding
>> this diff hunk you'll see a call to copy-sequence.
>>
>> My reasons for making this particular change are:
>> 0. Since Emacs 24.4, make-text-button has returned its modified first
>> argument, so callers can use the value returned by make-text-button
>> instead of calling it only for its side effects.
>> 1. This has now been reverted again, but for the last month,
>> make-text-button returned a modified _copy_ of its argument, which
>> meant that its side effects could no longer be relied upon.
>>
>> Either way, relying on its return value rather than its side effects
>> seems like the best style to stick with for now.
>
> So, IIUC `make-text-button` should ideally work functionally, but for
> historical reasons it works by side-effect. What's the long term plan?
> Do we plan to live with the current side-effecting behavior, or do we
> plan to move to the "pure" functional behavior?
>
> If we could detect when a string-button is "used" (i.e. displayed or
> inserted into a buffer), then we could detect the use of the old
> side-effecting style (by checking if the string passed as argument had
> already been displayed/inserted elsewhere) and emit a good warning.
AFAIK all relevant future plans are being discussed in this thread:
https://lists.gnu.org/archive/html/emacs-devel/2020-06/msg00117.html
For almost a month make-text-button was pure wrt strings, but that's now
been reverted again for backward compatibility and until a new decision
is reached.
--
Basil
next prev parent reply other threads:[~2020-06-05 13:50 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20200604223056.17078.81265@vcs0.savannah.gnu.org>
[not found] ` <20200604223058.1850020A26@vcs0.savannah.gnu.org>
2020-06-04 22:44 ` master f51f963: Fix some side-effecting uses of make-text-button Stefan Monnier
2020-06-05 0:58 ` Paul Eggert
2020-06-05 9:27 ` Pip Cet
2020-06-05 10:51 ` Basil L. Contovounesios
2020-06-05 12:46 ` Pip Cet
2020-06-05 13:51 ` Basil L. Contovounesios
2020-06-05 14:31 ` Pip Cet
2020-06-05 15:48 ` Basil L. Contovounesios
2020-06-05 18:17 ` Paul Eggert
2020-06-06 8:18 ` Pip Cet
2020-06-06 16:57 ` Drew Adams
2020-06-06 17:57 ` Stefan Monnier
2020-06-06 19:00 ` Pip Cet
2020-06-06 19:49 ` Paul Eggert
2020-06-06 20:23 ` Drew Adams
2020-06-07 9:14 ` Pip Cet
2020-06-06 22:14 ` Stefan Monnier
2020-06-07 1:40 ` Paul Eggert
2020-06-07 15:24 ` Stefan Monnier
2020-06-07 23:42 ` Paul Eggert
2020-06-07 9:31 ` Pip Cet
2020-06-06 20:19 ` Drew Adams
2020-06-06 17:54 ` Paul Eggert
2020-06-06 19:41 ` Pip Cet
2020-06-06 20:15 ` Paul Eggert
2020-06-07 9:21 ` Pip Cet
2020-06-07 23:37 ` Paul Eggert
2020-06-06 20:11 ` Drew Adams
2020-06-06 22:16 ` Stefan Monnier
2020-06-06 23:27 ` Drew Adams
2020-06-05 13:02 ` Stefan Monnier
2020-06-05 13:50 ` Basil L. Contovounesios [this message]
2020-06-06 19:09 ` Paul Eggert
2020-06-06 20:19 ` Drew Adams
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