From: Lars Ingebrigtsen <larsi@gnus.org>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: okamsn@protonmail.com, 49809@debbugs.gnu.org, monnier@iro.umontreal.ca
Subject: bug#49809: [PATCH] Add macro 'pcase-setq'
Date: Wed, 11 Aug 2021 23:57:29 +0200 [thread overview]
Message-ID: <87czqjod9y.fsf@gnus.org> (raw)
In-Reply-To: <87eeb6dmvo.fsf@web.de> (Michael Heerdegen's message of "Sat, 07 Aug 2021 04:11:55 +0200")
Michael Heerdegen <michael_heerdegen@web.de> writes:
>> +(defmacro pcase-setq (pat val &rest args)
>> + "Assign values to variables by destructuring with `pcase'.
>> +
>> +\(fn PATTERN VALUE PATTERN VALUE ...)"
It seems like there was general agreement to adding this, so I've now
applied Earl's patch, with the following addition to the doc string:
> Can we maybe enhance the docstring a bit? I think we should at least
> cover these points:
>
> - The PATTERNs are normal `pcase' patterns, the VALUES are expressions.
>
> - Evaluation happens sequentially as in `setq' (not in parallel)
>
> - When a PATTERN doesn't match it's VALUE, the pair is silently skipped
> (completely, no partial assignments are performed, AFAIU)
>
> Maybe adding a simple example would not be too bad as well?
Stefan Monnier <monnier@iro.umontreal.ca> writes:
> The result is the same whether `pcase-setq` assigns nil or doesn't touch
> the vars, so this test is not very effective. I'd rather do:
>
> (should (equal (list nil nil)
> (let ((a 'unset)
> (b 'unset))
> (pcase-setq `(,a ,b) nil)
> (list a b))))
I've also added this to the tests, but what it actually returns
instead...
> But Michael points out that it seems your code won't perform the
> assignment if the pattern doesn't match, which I find to be an
> odd behavior.
>
> I'd expect a behavior like that of `pcase-let`, instead.
... because I have no opinion here, really -- behaving like `pcase-let'
would be good, but on the other hand, the current behaviour also kinda
sorta makes sense.
So feel free to adjust the behaviour (or not).
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2021-08-11 21:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-01 17:20 bug#49809: [PATCH] Add macro 'pcase-setq' Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-04 7:14 ` Lars Ingebrigtsen
2021-08-04 23:06 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-05 1:02 ` Michael Heerdegen
2021-08-05 13:34 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-05 15:00 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-06 1:42 ` Michael Heerdegen
2021-08-06 4:07 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-06 4:28 ` Michael Heerdegen
2021-08-06 22:33 ` Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-07 2:11 ` Michael Heerdegen
2021-08-11 21:57 ` Lars Ingebrigtsen [this message]
2021-08-12 6:13 ` Michael Heerdegen
2021-08-12 12:11 ` Okam via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-12 15:06 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-13 2:55 ` Michael Heerdegen
2021-08-13 5:17 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-13 5:26 ` Michael Heerdegen
2021-08-07 15:42 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-09 0:28 ` Michael Heerdegen
2021-08-09 12:51 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
2021-08-10 3:13 ` Michael Heerdegen
2021-08-12 16:13 ` Stefan Monnier via Bug reports for GNU Emacs, the Swiss army knife of text editors
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