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From: Drew Adams <drew.adams@oracle.com>
To: Eli Zaretskii <eliz@gnu.org>, npostavs@users.sourceforge.net
Cc: 23926@debbugs.gnu.org
Subject: bug#23926: defcustom with STANDARD=<non-pure-expression> gives confusing results
Date: Sun, 10 Jul 2016 10:18:27 -0700 (PDT)	[thread overview]
Message-ID: <39c015f2-3ebf-43e8-9a37-9b50382042a7@default> (raw)
In-Reply-To: <<83k2gtfue4.fsf@gnu.org>>

> whoever uses current-time-string as a defcustom's value tells Emacs that
> the value is not important, because the programmer has no idea when in
> the process of building and restarting Emacs will the value be taken.
> Why does it make sense to rock the boat in this sensitive area for such
> use cases?

Obviously, `(current-time)' was an example, to demo show the problem.

It can sometimes make a lot of sense for a defcustom to use a sexp
that might not return the same result when reevaluated.

The original bug, from which this report is an offshoot, was #4755.
The example there used this defcustom sexp: `(copy-sequence foo)'.

And in the context of the using code there is nothing wrong with
such a sexp: the intention is really to use, as default value, a
(new) list whose elements are the (exact same) elements as those
in the list `foo'.

And yes, this (intentionally) means that the user option, `toto',
that has this value can share the objects that are its initial
elements.  Nothing wrong with using such an initial value for a
user option.

The problem is not with being able to make use of such a sexp for
the default value.  The problem is with how Emacs talks about the
state of the option value.  It miscommunicates to users.  That's
what this bug is about: how Emacs talks about what is going on.





  parent reply	other threads:[~2016-07-10 17:18 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <<<CAM-tV-8cG3gLgf-A+wBYPZWNy2WPGFV3uEdNE7=ad3oq4rXmnw@mail.gmail.com>
     [not found] ` <<<83vb0fgu83.fsf@gnu.org>
     [not found]   ` <<443f2e44-5167-48e7-abc6-cce1e243461e@default>
     [not found]     ` <<8337nihpdw.fsf@gnu.org>
2016-07-09 14:59       ` bug#23926: defcustom with STANDARD=<non-pure-expression> gives confusing results Drew Adams
2016-07-09 16:52         ` Eli Zaretskii
2016-07-09 20:48           ` npostavs
2016-07-10 14:19             ` Eli Zaretskii
     [not found]           ` <<871t32ilm0.fsf@users.sourceforge.net>
     [not found]             ` <<83k2gtfue4.fsf@gnu.org>
2016-07-10 17:18               ` Drew Adams [this message]
2016-07-11 18:40                 ` Eli Zaretskii
     [not found] <<<<<CAM-tV-8cG3gLgf-A+wBYPZWNy2WPGFV3uEdNE7=ad3oq4rXmnw@mail.gmail.com>
     [not found] ` <<<<<83vb0fgu83.fsf@gnu.org>
     [not found]   ` <<<<443f2e44-5167-48e7-abc6-cce1e243461e@default>
     [not found]     ` <<<<8337nihpdw.fsf@gnu.org>
     [not found]       ` <<<c0dd88c2-51ef-4f4f-964c-f0254db970f7@default>
     [not found]         ` <<<83zipqg3e3.fsf@gnu.org>
     [not found]           ` <<ff33c2cc-337a-433b-a87a-0ea1814311d2@default>
     [not found]             ` <<83bn24c8io.fsf@gnu.org>
2016-07-12  0:53               ` Drew Adams
     [not found] <<CAM-tV-8cG3gLgf-A+wBYPZWNy2WPGFV3uEdNE7=ad3oq4rXmnw@mail.gmail.com>
     [not found] ` <<83vb0fgu83.fsf@gnu.org>
2016-07-09 14:09   ` Drew Adams
2016-07-09 14:12     ` Eli Zaretskii
     [not found]       ` <<c0dd88c2-51ef-4f4f-964c-f0254db970f7@default>
     [not found]         ` <<83zipqg3e3.fsf@gnu.org>
2016-07-10 17:18           ` Drew Adams
2016-07-11 18:52             ` Eli Zaretskii
2016-07-09  3:11 Noam Postavsky
2016-07-09  6:31 ` Drew Adams
2016-07-09  7:13 ` Eli Zaretskii
2016-07-09 11:54   ` npostavs
2016-07-09 12:31     ` Eli Zaretskii
2016-07-09 12:55       ` Noam Postavsky
2016-07-09 13:14         ` Eli Zaretskii
2016-07-09 13:48           ` Noam Postavsky
2016-07-09 14:03             ` Eli Zaretskii
2016-07-12  3:26               ` npostavs
2016-07-12  5:20                 ` Eli Zaretskii
2016-07-09 14:34             ` Drew Adams
     [not found]             ` <<8360sehps4.fsf@gnu.org>
2016-07-09 14:54               ` Drew Adams
2016-07-09 15:09                 ` Drew Adams
2016-07-10 17:23                 ` Drew Adams
2023-10-17 14:19 ` bug#23926: defcustom with STANDARD=<non-constant-expression> " Mauro Aranda
2023-10-17 14:29   ` Mauro Aranda
     [not found] <<<<CAM-tV-8cG3gLgf-A+wBYPZWNy2WPGFV3uEdNE7=ad3oq4rXmnw@mail.gmail.com>
     [not found] ` <<<<83vb0fgu83.fsf@gnu.org>
     [not found]   ` <<<443f2e44-5167-48e7-abc6-cce1e243461e@default>

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