From: dkcombs@panix.com (David Combs)
To: help-gnu-emacs@gnu.org
Subject: Re: Macro aborts even though regexp instance exists - Serious Bug
Date: Fri, 30 Nov 2012 21:57:50 +0000 (UTC) [thread overview]
Message-ID: <k9ba4u$8fo$1@reader1.panix.com> (raw)
In-Reply-To: mailman.11579.1351050855.855.help-gnu-emacs@gnu.org
In article <mailman.11579.1351050855.855.help-gnu-emacs@gnu.org>,
Kevin Rodgers <kevin.d.rodgers@gmail.com> wrote:
>On 10/22/12 2:40 PM, Swami Tota Ram Shankar wrote:
>> Hi emacs users,
>>
>> I write a simple macro which works, however, it fails in a particular
>> case.
>>
>> C-s
>> M-r
>>
>> to get into isearch-forward-regexp
>>
>> and give a regexp like
>>
>> ONE\|TWO
>>
>> It works for every TWO and ONE as long as there is a ONE ahead of TWO.
>> In the last instance, no ONE exists after TWO and it fails.
>>
>> \|<=> OR or disjunction.
>>
>> Any solutions?
>>
>> This is such a fundamental issue that I think its a bug. When the C-s
>> M-r is used outside the macro definition, the cursor gladly returns
>> to the original position when OR is entered and proceeds forward from
>> there, but perhaps, the macro aborts.
>
>It is not a bug: when ONE fails to match the buffer, C-s (which is designed
>for interactive use, obviously) signals an error, which terminates the macro
>execution.
>
>That's because there is no way for C-s to know that you _might_ type \|TWO
>after ONE.
>
>So the solution is to make sure that the regexp is not complete after ONE:
>C-s \(ONE\|TWO\)
>
>> I guess, this can lead to a lot of confusion and time wastage, if the
>> user is unaware of this and most likely to neglect it because its
>> contrary to normal usage.
>
>Yes, there is a lot of confusion and wasted time when a user is not aware
>of how to use a program.
>
>> I include more newsgroups because of the seriousness of this bug.
>
>Whatever :-)
>
>--
>Kevin Rodgers
>Denver, Colorado, USA
>
>
(1) THANKS FOR THAT HINT/WARNING/INFO!
(2) "when a user is not aware of how to use a program": I don't know
that this thread really falls under that. Although your solution
and especially the reason for it "obvious" -- but only once you've
seen it. It's actually a little subtle.
AND I believe it's so important (and easy to get wrong) that
it should be added to the emacs manual (in macros) AND to
any much-used cheat-sheets -- plus the wiki, of course.
Perhaps you (as one of the real gurus around here) could write
a paragraph and example and ask the developers to put it into
the right places.
Thanks again for the pointer!
David
next prev parent reply other threads:[~2012-11-30 21:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-22 20:40 Macro aborts even though regexp instance exists - Serious Bug Swami Tota Ram Shankar
2012-10-24 3:54 ` Kevin Rodgers
[not found] ` <mailman.11579.1351050855.855.help-gnu-emacs@gnu.org>
2012-10-25 2:55 ` gnuist007
2012-11-30 21:57 ` David Combs [this message]
2012-11-30 22:55 ` Dan Espen
2012-12-03 14:33 ` Doug Lewan
[not found] ` <mailman.14392.1354545130.855.help-gnu-emacs@gnu.org>
2012-12-03 16:22 ` Dan Espen
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