From: michael@cadilhac.name (Michaël Cadilhac)
Cc: emacs-devel@gnu.org, Stefan Monnier <monnier@iro.umontreal.ca>,
Roland.Winkler@physik.uni-erlangen.de
Subject: Re: fortran-fill-paragraph fails
Date: Sat, 30 Dec 2006 13:56:45 +0100 [thread overview]
Message-ID: <87ejqhwnhu.fsf@lrde.org> (raw)
In-Reply-To: E1H0XdS-00032t-Uo@fencepost.gnu.org
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Richard Stallman <rms@gnu.org> writes:
> There's nothing specific to elisp there, and the \0 is just some
> arbitrary char: a space would have probably worked just as well.
>
> What purpose does that character serve? Is the aim to prevent the
> regexp from ever matching, in practice?
No! The aim of \0 is to prevent the match when the regexp is "^C",
for example, but also "^x?C" (no mode does that AFAIK, but it's just
a security) where x is any non regexp-special char except \0.
Suppose commark is `C', we will have :
(string-match "^C" (concat "\0" commark "a")) -> nil
(string-match "C" (concat "\0" commark "a")) -> 1
(string-match "^ ?C" (concat "\0" commark "a")) -> nil
If ` ' was used instead of "\0", the last one would have returned 0.
Of course, it doesn't prevent a regexp like "^.C", but we can suppose,
IMO, that no mode will do that. And IMO, it would be overkill to do
something to prevent that. "\0" is just a more secure char in this
precise context, at no cost :-) (except this thread ;-))
--
| Michaël `Micha' Cadilhac | In a World without Walls and Fences, |
| Epita/LRDE Promo 2007 | who needs Windows and Gates? |
| http://michael.cadilhac.name | -- Dino Esposito |
`--JID: michael.cadilhac@gmail.com--' - --'
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next prev parent reply other threads:[~2006-12-30 12:56 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <m3r6uq778w.fsf@tfkp07.physik.uni-erlangen.de>
2006-12-24 0:15 ` fortran-fill-paragraph fails Michaël Cadilhac
2006-12-24 1:35 ` Roland Winkler
2006-12-24 20:26 ` Michaël Cadilhac
2006-12-25 23:00 ` Stefan Monnier
2006-12-27 17:12 ` Roland Winkler
2006-12-29 21:06 ` Stefan Monnier
2006-12-29 22:43 ` Michaël Cadilhac
2006-12-30 6:24 ` Richard Stallman
2006-12-30 12:56 ` Michaël Cadilhac [this message]
2006-12-31 1:45 ` Richard Stallman
2007-01-02 23:22 ` Stefan Monnier
2007-01-03 21:11 ` Richard Stallman
2007-01-07 20:12 ` Stefan Monnier
2006-12-30 16:04 ` Roland Winkler
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