GNU bug report logs - #23105
25.0.92; map-put does not change its argument MAP

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Message #30 received at 23105 <at> debbugs.gnu.org (full text, mbox):

From: Sho Takemori <stakemorii <at> gmail.com>
To: Nicolas Petton <nicolas <at> petton.fr>
Cc: 23105 <at> debbugs.gnu.org
Subject: Re: bug#23105: 25.0.92; map-put does not change its argument MAP
Date: Sat, 26 Mar 2016 00:20:49 +0900

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OK. Thanks for the reply.


2016-03-26 0:14 GMT+09:00 Nicolas Petton <nicolas <at> petton.fr>:

> Sho Takemori <stakemorii <at> gmail.com> writes:
>
> > Thanks for the fix. But after the fix, if MAP is a list literal, then it
> > raises an error.
> > For example, this raises an error.
> > (map-put '((a . 1)) 'a "value")
> >
> > This works.
> > (map-put [0 1 2] 1 "value")
> >
> > It is an expected error?
>
> Yes, in the sense that the same error will be raised if you try to do it
> with a setf on an alist:
>
> (setf (alist-get 'b '((a . 1))) 3) ;; => invalid-function (a . 1)
>
> (let ((alist '((a . 1))))
>   (setf (alist-get 'b alist) 3)) ;; => works fine
>
> Note however that mutating literal lists is in general not a good idea,
> as conses might be shared.
>
> Nico
>

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