GNU bug report logs - #35206
[PATCH] Misleading `list-get' argument description

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Mattias Engdegård <mattiase <at> acm.org>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#35206: closed ([PATCH] Misleading `list-get' argument
 description)
Date: Tue, 09 Apr 2019 15:00:02 +0000

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Your message dated Tue, 9 Apr 2019 16:59:48 +0200
with message-id <948BCACD-D6CE-46AD-A31A-82272AB1A077 <at> acm.org>
and subject line Re: bug#35206: [PATCH] Misleading `list-get' argument description
has caused the debbugs.gnu.org bug report #35206,
regarding [PATCH] Misleading `list-get' argument description
to be marked as done.

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help-debbugs <at> gnu.org.)


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From: Mattias Engdegård <mattiase <at> acm.org>
To: bug-gnu-emacs <at> gnu.org
Subject: [PATCH] Misleading `list-get' argument description
Date: Tue, 9 Apr 2019 12:34:09 +0200

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The doc string for `list-get' says

  Use TESTFN to lookup in the alist if non-nil.  Otherwise, use `assq'.

which is misleading since it's an equality predicate, not a look-up function, and the default is `eq', not `assq'.
How about changing it to

  Equality is defined by TESTFN or by `eq' if nil or omitted.

[0001-Clarify-the-TESTFN-argument-to-alist-get.patch (application/octet-stream, attachment)]

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From: Mattias Engdegård <mattiase <at> acm.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 35206-done <at> debbugs.gnu.org
Subject: Re: bug#35206: [PATCH] Misleading `list-get' argument description
Date: Tue, 9 Apr 2019 16:59:48 +0200

9 apr. 2019 kl. 16.41 skrev Eli Zaretskii <eliz <at> gnu.org>:
> 
>  Find an element of ALIST whose `car' equals KEY and return its `cdr'.
>  ...
>  Equality with KEY is tested by TESTFN, defaulting to `eq'.

Thank you, I pushed that change (except that I used "the first element" instead of "an element" for precision).

> IMO, this isn't about assuming knowledge, this is about being as
> explicit as reasonably possible about what the function does.
> (Strictly speaking, both your suggestion and mine still assume some
> knowledge about alists, because we never explain what is an alist, nor
> what is an "element" of an alist.)

That's all right -- I was mainly concerned with the quite misleading TESTFN description, and looked at the docs of similar functions (assq, assoc).

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