bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

[Ian Eure]

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A user came into #emacs today complaining that his paren matching was  
not working with a large file, and that font-locking broke as a result.

I found that this is controlled by blink-matching-paren-distance,  
which was increased to 25kb around 1997.

Attached is a patch which doubles this to 50kb, as this should be fine  
for modern machines. I think that we should seriously consider setting  
the default to nil, but this seems like a more conservative approach  
to the matter.


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Index: simple.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/simple.el,v
retrieving revision 1.998
diff -u -u -r1.998 simple.el
--- simple.el	19 Jul 2009 00:33:11 -0000	1.998
+++ simple.el	20 Jul 2009 20:45:21 -0000
@@ -5254,7 +5254,7 @@
   :type 'boolean
   :group 'paren-blinking)
 
-(defcustom blink-matching-paren-distance (* 25 1024)
+(defcustom blink-matching-paren-distance (* 50 1024)
   "If non-nil, maximum distance to search backwards for matching open-paren.
 If nil, search stops at the beginning of the accessible portion of the buffer."
   :type '(choice (const nil) integer)

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bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

[martin rudalics]

 > A user came into #emacs today complaining that his paren matching was
 > not working with a large file, and that font-locking broke as a result.
 >
 > I found that this is controlled by blink-matching-paren-distance, which
 > was increased to 25kb around 1997.

How can `blink-matching-paren-distance' affect font-locking?  If I
understand correctly all `blink-matching-open' can do is slow down
typing.

martin

bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

[Ian Eure]

On Jul 21, 2009, at 2:39 AM, martin rudalics wrote:

> > A user came into #emacs today complaining that his paren matching  
> was
> > not working with a large file, and that font-locking broke as a  
> result.
> >
> > I found that this is controlled by blink-matching-paren-distance,  
> which
> > was increased to 25kb around 1997.
>
> How can `blink-matching-paren-distance' affect font-locking?  If I
> understand correctly all `blink-matching-open' can do is slow down
> typing.
>
I don't know, as I couldn't reproduce that aspect of the issue.  
Perhaps their `show-paren-style' was set to 'expression.

The paren matching definitely breaks, though. You get a message saying  
that you have mismatched parens, and they're highlighted incorrectly.

  - Ian

bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

[martin rudalics]

 > I don't know, as I couldn't reproduce that aspect of the issue. Perhaps
 > their `show-paren-style' was set to 'expression.

Could you try to get back to them?  Font-locking should never be
affected by this.

 > The paren matching definitely breaks, though. You get a message saying
 > that you have mismatched parens, and they're highlighted incorrectly.

That's normal.

martin

bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance

[Stefan Monnier]

> Attached is a patch which doubles this to 50kb, as this should be fine for
> modern machines.

100kB should be fine, indeed.

> I think that we should seriously consider setting the default to nil,
> but this seems like a more conservative approach to the matter.

Maybe when you're browsing a 200MB log file, you'll find it painful, so
a lower limit would still seem to make sense.  100kB is probably very
conservative (even when running on my poor cell-phone, it should be fast
enough).


        Stefan

bug#3889: marked as done (23.1.50; [PATCH] Increase blink-matching-paren-distance)

[Emacs bug Tracking System]

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Your message dated Tue, 21 Jul 2009 22:35:50 -0400
with message-id <mf8wihe96h.fsf@fencepost.gnu.org>
and subject line Re: bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance
has caused the Emacs bug report #3889,
regarding 23.1.50; [PATCH] Increase blink-matching-paren-distance
to be marked as done.

This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
bug report if necessary, and/or fix the problem forthwith.

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-- 
3889: http://emacsbugs.donarmstrong.com/cgi-bin/bugreport.cgi?bug=3889
Emacs Bug Tracking System
Contact owner@emacsbugs.donarmstrong.com with problems

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A user came into #emacs today complaining that his paren matching was  
not working with a large file, and that font-locking broke as a result.

I found that this is controlled by blink-matching-paren-distance,  
which was increased to 25kb around 1997.

Attached is a patch which doubles this to 50kb, as this should be fine  
for modern machines. I think that we should seriously consider setting  
the default to nil, but this seems like a more conservative approach  
to the matter.


[-- Attachment #2.1.2: blink-matching-paren.patch --]
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Index: simple.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/simple.el,v
retrieving revision 1.998
diff -u -u -r1.998 simple.el
--- simple.el	19 Jul 2009 00:33:11 -0000	1.998
+++ simple.el	20 Jul 2009 20:45:21 -0000
@@ -5254,7 +5254,7 @@
   :type 'boolean
   :group 'paren-blinking)
 
-(defcustom blink-matching-paren-distance (* 25 1024)
+(defcustom blink-matching-paren-distance (* 50 1024)
   "If non-nil, maximum distance to search backwards for matching open-paren.
 If nil, search stops at the beginning of the accessible portion of the buffer."
   :type '(choice (const nil) integer)

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From: Glenn Morris <rgm@gnu.org>
To: 3889-done@emacsbugs.donarmstrong.com
Subject: Re: bug#3889: 23.1.50; [PATCH] Increase blink-matching-paren-distance
Date: Tue, 21 Jul 2009 22:35:50 -0400
Message-ID: <mf8wihe96h.fsf@fencepost.gnu.org>

Stefan Monnier wrote:

>> Attached is a patch which doubles this to 50kb, as this should be fine for
>> modern machines.
>
> 100kB should be fine, indeed.

So increased.