bug#50110: closed (26.3; Doc of `assoc': TESTFN optional arg)

[GNU bug Tracking System]

Your message dated Wed, 18 Aug 2021 22:08:53 +0300
with message-id <83mtpe370a.fsf@gnu.org>
and subject line Re: [External] : Re: bug#50110: 26.3; Doc of `assoc': TESTFN 
optional arg
has caused the debbugs.gnu.org bug report #50110,
regarding 26.3; Doc of `assoc': TESTFN optional arg
to be marked as done.

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> --- Begin Message ---
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> Subject: 
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> 26.3; Doc of `assoc': TESTFN optional arg
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> Date: 
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> Wed, 18 Aug 2021 17:36:11 +0000
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> Neither the `assoc' doc string nor the Elisp manual, node `Association
> Lists' explains the order of the args that get passed to TESTFN.
>
> It's just as reasonable to expect that the pattern is the first arg to
> TESTFN, instead of, as is actually the case, the second arg.
>
> E.g., one could suppose that this would work (return the first element):
>
> (setq trees '(("pine" . "cones") ("oak" . "acorns")))
>
> (assoc ".*ine" trees #'string-match-p)
>
> But in fact this is what you need:
>
> (assoc ".*ine" trees (lambda (x regexp) (string-match-p regexp x)))
>
> Please consider documenting the arg order for TESTFN.
>
> In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
>  of 2019-08-29
> Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
> Windowing system distributor `Microsoft Corp.', version 10.0.19042
> Configured using:
>  `configure --without-dbus --host=x86_64-w64-mingw32
>  --without-compress-install 'CFLAGS=-O2 -static -g3''
>
>
>
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> --- End Message ---
> --- Begin Message ---
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>
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> Subject: 
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> Re: [External] : Re: bug#50110: 26.3; Doc of `assoc': TESTFN optional arg
>
>
>
>
> Date: 
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> Wed, 18 Aug 2021 22:08:53 +0300
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>
>
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> > From: Drew Adams <drew.adams@oracle.com>
> > CC: "50110@debbugs.gnu.org" <50110@debbugs.gnu.org>
> > Date: Wed, 18 Aug 2021 18:41:00 +0000
> > 
> > > > Neither the `assoc' doc string nor the Elisp manual, node `Association
> > > > Lists' explains the order of the args that get passed to TESTFN.
> > > 
> > > It's a function that tests 2 objects for equality, so why does the
> > > order matter?
> > > 
> > > > It's just as reasonable to expect that the pattern is the first arg to
> > > > TESTFN, instead of, as is actually the case, the second arg.
> > > 
> > > There's no "pattern" in the doc string, so I don't think I understand
> > > what you are describing here.
> > 
> > I gave examples.  What part is unclear?  To know how to use
> > `string-match-p' for testing you need to know the arg order
> > for TESTFN.  The arg order matters for `string-match-p'.
>
> OK, I added description of how TESTFN is called.
>
>
> --- End Message ---