From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Le Wang <l26wang@gmail.com>
Cc: Lars Magne Ingebrigtsen <larsi@gnus.org>,
Andreas Schwab <schwab@linux-m68k.org>,
9469@debbugs.gnu.org
Subject: bug#9469: buffer-local variables seem to remember previous values
Date: Tue, 13 Sep 2011 08:54:58 -0400 [thread overview]
Message-ID: <jwvzki8obem.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <CAM=K+iqeV-FWux56FsG7qJNzW4gzFT93Fxw1w47ac6PQhpcdnA@mail.gmail.com> (Le Wang's message of "Mon, 12 Sep 2011 12:39:13 +0800")
> "The special form quote returns its single argument, as written,
> without evaluating it. This provides a way to include constant symbols
> and lists"
> Isn't the first sentence misleading? It does not *always* return a
> single argument as written. It does the first time, and memoizes
> subsequently. Where is the mention of that?
There is no memoization: the quote does not *construct* the object, it
just returns it.
The problem is similar/identical to what happens with immediate strings in C:
char *foo (void)
{
char *res = "toto\n";
res[1]++;
return res;
}
[ modern C tries to fix this problem by the use of "const char*". ]
> Again, pedantically speaking, the information is there. It's just not
> clear enough to prevent other people falling into this trap in the
> future.
I'd be happy to try and make it more clear to people who aren't familiar
with it (after all, that's the main target audience here), but I'm not
sure how.
Do you have some suggestion about what text to use to make it clear to you?
Stefan
next prev parent reply other threads:[~2011-09-13 12:54 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-10 17:07 bug#9469: buffer-local variables seem to remember previous values Le Wang
2011-09-10 17:44 ` Drew Adams
2011-09-11 16:57 ` Le Wang
2011-09-11 17:56 ` Drew Adams
2011-09-11 18:08 ` Andreas Schwab
2011-09-11 18:49 ` Le Wang
2011-09-11 18:54 ` Lars Magne Ingebrigtsen
2011-09-11 19:18 ` Le Wang
2011-09-11 19:54 ` Lars Magne Ingebrigtsen
2011-09-12 4:39 ` Le Wang
2011-09-12 7:57 ` Andreas Schwab
2011-09-12 8:23 ` Le Wang
2011-09-12 8:35 ` Andreas Schwab
2011-09-12 14:30 ` Drew Adams
2011-09-12 15:06 ` Le Wang
2011-09-13 12:54 ` Stefan Monnier [this message]
2011-09-13 13:12 ` Le Wang
2011-09-13 15:00 ` Helmut Eller
2011-09-13 18:02 ` Johan Bockgård
2011-09-13 18:52 ` Drew Adams
2011-09-13 20:42 ` Helmut Eller
2011-09-15 18:14 ` Le Wang
2011-09-11 19:37 ` Helmut Eller
2011-09-11 19:46 ` Andreas Schwab
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwvzki8obem.fsf-monnier+emacs@gnu.org \
--to=monnier@iro.umontreal.ca \
--cc=9469@debbugs.gnu.org \
--cc=l26wang@gmail.com \
--cc=larsi@gnus.org \
--cc=schwab@linux-m68k.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.