From: Eric Abrahamsen <eric@ericabrahamsen.net>
To: Noam Postavsky <npostavs@gmail.com>
Cc: 31584@debbugs.gnu.org
Subject: bug#31584: 27.0.50; Document again what match re-search-backward finds
Date: Thu, 24 May 2018 15:47:22 -0700 [thread overview]
Message-ID: <87k1rsfz7p.fsf@ericabrahamsen.net> (raw)
In-Reply-To: <87wovsg0q3.fsf@gmail.com> (Noam Postavsky's message of "Thu, 24 May 2018 18:14:44 -0400")
On 05/24/18 18:14 PM, Noam Postavsky wrote:
> The docstring should definitely be clarified, but technically it can
> still be answered, if you read very carefully:
If reading the documentation takes only a little less effort than
reading the code...
>> I've been bitten by this before. I'm sure the sentence you cite is,
>> correct, but I would suggest something more explicit about backwards
>> searches. The most useful thing I could have read when I was wondering
>> why this didn't work would be something like: "re-search-backward always
>> behaves "non-greedily", i.e., it will find the shortest match before
>> point".
>
> It is greedy:
>
> (with-temp-buffer
> (insert "xxxxyyyy")
> (and (re-search-backward "x+y*" nil t)
> (match-string 0))) ;=> "xyyyy"
>
> Non-greedy wouldn't match any "y"s. It's a bit tricky to explain both
> correctly and clearly...
Yeah, my wording is bad. I think an example might be most clear. Maybe:
#+BEGIN_SRC elisp
(with-temp-buffer
(let ((re "x+y+"))
(insert "xxxxyyyy")
(goto-char (point-min))
(re-search-forward re nil t)
(match-string 0) => "xxxxyyyy"
(goto-char (point-max))
(re-search-backward re nil t)
(match-string 0))) => "xyyyy"
#+END_SRC
Or if there's something more concise...
next prev parent reply other threads:[~2018-05-24 22:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-24 21:31 bug#31584: 27.0.50; Document again what match re-search-backward finds Michael Heerdegen
2018-05-24 21:42 ` Eric Abrahamsen
2018-05-24 21:59 ` Michael Heerdegen
2018-05-24 22:10 ` Eric Abrahamsen
2018-05-24 22:14 ` Noam Postavsky
2018-05-24 22:47 ` Eric Abrahamsen [this message]
2018-05-24 22:47 ` Michael Heerdegen
2018-05-24 23:55 ` Noam Postavsky
2018-05-25 0:22 ` Michael Heerdegen
2018-05-25 0:31 ` Noam Postavsky
2018-05-25 0:36 ` Eric Abrahamsen
2018-05-25 1:10 ` Michael Heerdegen
2018-05-25 1:27 ` Noam Postavsky
2018-05-25 1:48 ` Michael Heerdegen
2018-05-25 6:23 ` Eli Zaretskii
2018-05-25 11:59 ` Noam Postavsky
2018-05-25 0:28 ` Drew Adams
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