From: Robert Pluim <rpluim@gmail.com>
To: tomas@tuxteam.de
Cc: "help-gnu-emacs@gnu.org" <help-gnu-emacs@gnu.org>
Subject: Re: Dash in regexp character classes: Beginnig vs. end [was: Use the characters "+" and "-" in regular expressions]
Date: Thu, 20 May 2021 10:08:37 +0200 [thread overview]
Message-ID: <87lf896d4q.fsf@gmail.com> (raw)
In-Reply-To: <20210520071529.GA1127@tuxteam.de> (tomas@tuxteam.de's message of "Thu, 20 May 2021 09:15:29 +0200")
>>>>> On Thu, 20 May 2021 09:15:29 +0200, "tomas@tuxteam.de" <tomas@tuxteam.de> said:
>> I quoted this from (elisp) `Regexp Special':
>>
>> To include a ‘-’, write ‘-’ as the first or last
>> ^^^^^^^^^^^^^
>> character of the character alternative, or as the
>> upper bound of a range. Thus, ‘[]-]’ matches both
>> ‘]’ and ‘-’.
>>
>> That's from Emacs 26 (and all prior releases, at least
>> as far back as Emacs 20). But yes, they changed that
>> text for Emacs 27, to this:
>>
>> To include ‘-’, put it at the end.
>> ^^^^^^^^^^
>> ___
>>
>> For Emacs 20, it says this:
>>
>> To include a `-', write `-' as the first or last
>> character of the character alternative, or put it
>> after a range. Thus, `[]-]' matches both `]' and
>> `-'.
tomas@tuxteam> Oh. That is interesting. Anyone knows why that change?
It makes the description and usage simpler and more regular, and less
error-prone.
Since I never remember the rules for this stuff anyway, I do this
instead:
(rx (or ?- ?+ ?.))
=> "[+.-]"
but of course parenthesis-like characters still need to be escaped:
(rx (or ?\) ?\] ?-))
=> "[])-]"
Robert
--
next prev parent reply other threads:[~2021-05-20 8:08 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-19 16:07 Use the characters "+" and "-" in regular expressions steve-humphreys
2021-05-19 16:17 ` Skip Montanaro
2021-05-19 16:26 ` steve-humphreys
2021-05-19 16:47 ` Yuri Khan
2021-05-19 17:39 ` steve-humphreys
2021-05-19 19:16 ` tomas
2021-05-19 19:27 ` tomas
2021-05-19 19:30 ` Yuri Khan
2021-05-19 21:32 ` tomas
2021-05-19 21:59 ` [External] : " Drew Adams
2021-05-20 6:26 ` RE: [External] : " steve-humphreys
2021-05-20 7:59 ` steve-humphreys
2021-05-20 8:26 ` tomas
2021-05-20 8:41 ` steve-humphreys
2021-05-20 9:42 ` steve-humphreys
2021-05-20 9:56 ` tomas
2021-05-20 10:11 ` steve-humphreys
2021-05-20 10:22 ` tomas
2021-05-20 10:37 ` steve-humphreys
2021-05-20 10:50 ` tomas
2021-05-20 11:19 ` steve-humphreys
2021-05-20 11:27 ` steve-humphreys
2021-05-20 12:04 ` tomas
2021-05-20 11:31 ` Christopher Dimech
2021-05-20 11:40 ` steve-humphreys
2021-05-20 11:49 ` Christopher Dimech
2021-05-20 13:03 ` Jean Louis
2021-05-20 11:59 ` tomas
2021-05-20 12:53 ` Jean Louis
2021-05-20 12:46 ` Jean Louis
2021-05-20 13:55 ` steve-humphreys
2021-05-20 14:14 ` Jean Louis
2021-05-20 14:28 ` steve-humphreys
2021-05-20 16:24 ` Yuri Khan
2021-05-20 16:34 ` steve-humphreys
2021-05-20 17:16 ` Eduardo Ochs
2021-05-20 18:29 ` Drew Adams
2021-05-21 5:48 ` Jean Louis
2021-05-20 12:39 ` Jean Louis
2021-05-20 7:15 ` Dash in regexp character classes: Beginnig vs. end [was: Use the characters "+" and "-" in regular expressions] tomas
2021-05-20 8:08 ` Robert Pluim [this message]
2021-05-19 19:26 ` [External] : Re: Use the characters "+" and "-" in regular expressions Drew Adams
2021-05-19 19:25 ` Drew Adams
2021-05-19 16:27 ` tomas
2021-05-19 16:39 ` Skip Montanaro
2021-05-19 17:43 ` Marcin Borkowski
2021-05-19 19:10 ` tomas
2021-05-19 19:17 ` [External] : " Drew Adams
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