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From: David Kastrup <dak@gnu.org>
To: emacs-devel@gnu.org
Subject: Re: `save-excursion' defeated by `set-buffer'
Date: Mon, 04 Jan 2010 18:34:50 +0100	[thread overview]
Message-ID: <87wrzxwz7p.fsf@lola.goethe.zz> (raw)
In-Reply-To: 47994.130.55.118.19.1262624933.squirrel@webmail.lanl.gov

"Davis Herring" <herring@lanl.gov> writes:

>> save-excursion only saves point in the current buffer, so
>>
>>    (save-excursion (set-buffer foo) (goto-char (point-min)))
>>
>> will move point in foo and the point-saving done by save-excursion is
>> useless.  So either you want to use
>
> If we know that (eq foo (current-buffer)), we should drop the
> `set-buffer'.  If we know that not to be the case, we should use
> `with-current-buffer' (or perhaps `save-current-buffer').  But what if it
> could but needn't be?

And what if we don't have just (goto-char (point-min)), but some code
that might _revisit_ the original buffer (with set-buffer or otherwise)
and _move_ its point?  Then save-excursion _will_ restore the original
point in the buffer at its end which otherwise would remain moved.

-- 
David Kastrup





  reply	other threads:[~2010-01-04 17:34 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-12-20 19:19 `save-excursion' defeated by `set-buffer' Roland Winkler
2009-12-21 15:26 ` Stefan Monnier
2009-12-21 16:23   ` David Kastrup
2009-12-22 12:51     ` martin rudalics
2009-12-23  0:45     ` Stefan Monnier
2009-12-23  9:07       ` David Kastrup
2009-12-24  4:35         ` Stefan Monnier
2009-12-24  9:03           ` David Kastrup
2009-12-29 16:01             ` Stefan Monnier
2010-01-04  9:09               ` Drew Adams
2010-01-04 18:30                 ` Stefan Monnier
2010-01-05 20:17                   ` David Kastrup
2010-01-06  0:02                     ` Drew Adams
2010-01-06  4:20                       ` Stefan Monnier
2010-01-06  8:07                         ` David Kastrup
2010-01-06  8:57                           ` Drew Adams
2010-01-10  4:57                             ` Stefan Monnier
2010-01-10  8:12                               ` David Kastrup
2010-01-10 21:43                                 ` Stefan Monnier
2010-01-11  8:24                                   ` David Kastrup
2010-01-11  9:21                                     ` martin rudalics
2010-01-11 16:50                                       ` Stefan Monnier
2010-01-10 17:03                               ` Drew Adams
2010-01-10  4:51                           ` Stefan Monnier
2010-01-10 15:58                         ` Harald Hanche-Olsen
2010-01-10 18:05                           ` martin rudalics
2010-01-10 18:06                           ` Drew Adams
2010-01-10 19:44                             ` Harald Hanche-Olsen
2009-12-24 14:04   ` Roland Winkler
2010-01-04 17:08   ` Davis Herring
2010-01-04 17:34     ` David Kastrup [this message]
2010-01-04 18:33     ` Stefan Monnier
  -- strict thread matches above, loose matches on Subject: below --
2009-12-18  9:20 Eli Zaretskii
2009-12-18 15:29 ` Juanma Barranquero
2009-12-18 15:58   ` Thierry Volpiatto

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