From: "Drew Adams" <drew.adams@oracle.com>
To: "'Eli Zaretskii'" <eliz@gnu.org>,
"'Andreas Schwab'" <schwab@linux-m68k.org>
Cc: 12314@debbugs.gnu.org, cyd@gnu.org
Subject: bug#12314: 24.2.50; `add-to-history': use `setq' with `delete'
Date: Sat, 8 Sep 2012 09:54:27 -0700 [thread overview]
Message-ID: <B06D754ADE5F4D82900E0C7A68BB4F28@us.oracle.com> (raw)
In-Reply-To: <838vckmq4c.fsf@gnu.org>
> > Even if the element is not the first one, you always have
> > to think about other references that may exist to the
> > cons that is removed.
>
> Sorry, I'm not sure how this is related. Please elaborate.
(Think pointers.) A variable stays pointed to the same cons cell - these
operations do not change that. But they can change the relations among cons
cells: which of them point to which others.
(setq a '(1 2 3 4))
(setq b (cddr a))
a => (1 2 3 4)
b => (3 4)
(delq 4 b)
a => (1 2 3)
b => (3)
The value of variable `a' was changed by changing the value of `b', because `b'
points to a cons cell that is used in the list structure pointed to by `a'.
next prev parent reply other threads:[~2012-09-08 16:54 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-30 23:08 bug#12314: 24.2.50; `add-to-history': use `setq' with `delete' Drew Adams
2012-09-08 14:32 ` Chong Yidong
2012-09-08 14:43 ` Eli Zaretskii
2012-09-08 14:57 ` Drew Adams
2012-09-08 15:20 ` Eli Zaretskii
2012-09-08 15:48 ` Drew Adams
2012-09-08 16:05 ` Eli Zaretskii
2012-09-08 16:19 ` Andreas Schwab
2012-09-08 16:33 ` Eli Zaretskii
2012-09-08 16:50 ` Lars Ingebrigtsen
2012-09-08 16:54 ` Drew Adams [this message]
2012-09-08 17:06 ` Andreas Schwab
2012-09-08 16:35 ` Drew Adams
2012-09-08 16:25 ` Drew Adams
2012-09-08 16:32 ` Eli Zaretskii
2012-09-08 16:42 ` Drew Adams
2012-09-08 21:21 ` Eli Zaretskii
2012-09-08 22:26 ` Drew Adams
2012-09-09 3:00 ` Eli Zaretskii
2012-09-09 6:29 ` Drew Adams
2012-09-09 7:53 ` Chong Yidong
2012-09-09 17:25 ` Eli Zaretskii
2012-09-10 11:54 ` Wolfgang Jenkner
2012-09-08 23:11 ` Stefan Monnier
2012-09-09 2:51 ` Eli Zaretskii
2012-09-09 14:44 ` Stefan Monnier
2012-09-09 17:14 ` Eli Zaretskii
2012-09-09 17:35 ` Drew Adams
2012-09-09 18:20 ` Eli Zaretskii
2012-09-09 19:46 ` Drew Adams
2012-09-09 21:37 ` Stefan Monnier
2012-09-10 4:37 ` Eli Zaretskii
2012-09-10 12:59 ` Stefan Monnier
2012-09-10 15:01 ` Stefan Monnier
2012-09-10 15:21 ` Drew Adams
2012-09-10 16:24 ` Eli Zaretskii
2012-09-09 8:25 ` Dmitry Gutov
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