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Filters and sentinels now save match data themselves.

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This commit is contained in:
Richard M. Stallman 1994-11-22 04:31:18 +00:00
parent 4f734bde41
commit d128025939
1 changed files with 10 additions and 13 deletions
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23
lispref/searching.texi
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@ -1106,15 +1106,10 @@ an error; that sets the match data in a meaningless but harmless way.
@node Saving Match Data
@subsection Saving and Restoring the Match Data
All asynchronous process functions (filters and sentinels) and
functions that use @code{recursive-edit} should save and restore the
match data if they do a search or if they let the user type arbitrary
commands. Saving the match data is useful in other cases as
well---whenever you want to access the match data resulting from an
earlier search, notwithstanding another intervening search.
This example shows the problem that can arise if you fail to
attend to this requirement:
When you call a function that may do a search, you may need to save
and restore the match data around that call, if you want to preserve the
match data from an earlier search for later use. Here is an example
that shows the problem that arises if you fail to save the match data:
@example
@group
@ -1127,13 +1122,11 @@ attend to this requirement:
@end group
@end example
In Emacs versions 19 and later, you can save and restore the match
data with @code{save-match-data}:
You can save and restore the match data with @code{save-match-data}:
@defspec save-match-data body@dots{}
This special form executes @var{body}, saving and restoring the match
data around it. This is useful if you wish to do a search without
altering the match data that resulted from an earlier search.
data around it.
@end defspec
You can use @code{set-match-data} together with @code{match-data} to
@ -1149,6 +1142,10 @@ useful for writing code that can run in Emacs 18. Here is how:
@end group
@end example
Emacs automatically saves and restores the match data when it runs
process filter functions (@pxref{Filter Functions}) and process
sentinels (@pxref{Sentinels}).
@ignore
Here is a function which restores the match data provided the buffer
associated with it still exists.