From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: Saving match data
Date: Wed, 28 Sep 2016 12:11:00 -0400 [thread overview]
Message-ID: <jwvlgyc9fof.fsf-monnier+gmane.emacs.devel@gnu.org> (raw)
In-Reply-To: CAArVCkQmYyxK2j+Ey4T_JgFNZpKkSDESoFPgudO70B9MZahtkw@mail.gmail.com
> I think this statement is surprising
Agreed. That's why we have to write it explicitly in the doc ;-)
> and puts unnecessary burden on Elisp programmers.
Experience shows that it's the more efficient choice, tho: both in terms
of CPU efficiency and in terms of programmer efficiency.
So, yes, I think it's definitely necessary.
> Taken literally, Elisp programmers need to surround even calls to
> `car' with `save-match-data' because the documentation of `car'
> doesn't specify that it doesn't change the match data.
Indeed, there's also an expectation that "primitives" don't touch the
match-data. It would be good to document it, tho it will take some work
to clarify what is meant by "primitive".
> "Notice that no functions are allowed to overwrite the match data unless
> they're explicitly documented to do so."
> and then clean up existing documentation and add `save-match-data' where
> appropriate.
That would imply adding save-match-data *everywhere*. It's an enormous
amount of work, can't be automated, and comes with only two obvious results:
- our Elisp source code will be significantly larger.
- Emacs will be slower.
Stefan
next prev parent reply other threads:[~2016-09-28 16:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-28 14:01 Saving match data Philipp Stephani
2016-09-28 15:03 ` Eli Zaretskii
2016-09-28 16:11 ` Stefan Monnier [this message]
2016-09-28 16:49 ` Michael Heerdegen
2016-09-28 18:25 ` Stefan Monnier
2016-09-28 18:37 ` Michael Heerdegen
2016-09-28 20:00 ` Eli Zaretskii
2016-09-28 20:15 ` Michael Heerdegen
2016-09-28 20:22 ` Eli Zaretskii
2016-09-28 20:42 ` Michael Heerdegen
2016-09-28 20:58 ` Lars Ingebrigtsen
2016-09-29 2:36 ` Eli Zaretskii
2016-10-08 4:02 ` Michael Heerdegen
2016-10-08 6:25 ` Eli Zaretskii
2016-10-08 15:06 ` Stefan Monnier
2017-06-16 19:24 ` Philipp Stephani
2017-06-16 19:53 ` Stefan Monnier
2017-06-16 22:16 ` Philipp Stephani
2017-06-17 13:53 ` Stefan Monnier
2017-06-17 14:02 ` Philipp Stephani
2017-10-08 15:56 ` Philipp Stephani
2017-10-08 16:01 ` Philipp Stephani
2016-09-28 17:00 ` Marcin Borkowski
2016-09-29 9:29 ` Uwe Brauer
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