GNU bug report logs - #4312
23.1; save-excursion and goto-char fail

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From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: 4312 <at> debbugs.gnu.org, RSridhar <rsridar50 <at> dataone.in>,
        bug-gnu-emacs <at> gnu.org
Subject: bug#4312: 23.1;  save-excursion and goto-char fail
Date: Thu, 03 Sep 2009 18:33:01 +0200

Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

>> 1. I have a lisp code which saves file buffer and does some
>> manipulation on the file in shell.  subsequently it is reverted.
>> However I have tried save-excursion before saving file which did not
>> restore the file position on reverting.
>
> save-excursion uses markers to remember the position.  But markers only
> keep track of positions by keeping track of insertions/deletions and
> adjusting the position accordingly.  When the changes happen outside
> Emacs, this doesn't work too well, because Emacs sees your revert-buffer
> as just one big delete&insert.

insert-file-contents tries to keep markers if possible, but that only
works if the marker points into the unchanged head or tail of the
replaced contents.

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
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