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Re: extended rx.el

From: Dave Love
Subject: Re: extended rx.el
Date: Wed, 28 Apr 2004 11:29:45 +0100
User-agent: Gnus/5.1002 (Gnus v5.10.2) Emacs/21.2 (gnu/linux)

Stefan Monnier <address@hidden> writes:

> I'd rather keep this info close to the source code (i.e. regex.c)
> since it could change at any time.  I think people intuitively (and
> correctly with the current implementation) know/expect that
> \(?:foo\) will be slower than foo but faster than \(foo\) which is
> all that really matters.

But you said that's false!  \(?:foo\) normally isn't slower.

The issue is whether when generating regexps a la Rx, for instance,
you worry about extra groups and expend effort eliminating them (as Rx
already does, actually).

It would be useful to have the info _somewhere_ anyway -- regex.c is
far from transparent, I guess especially if you don't know/remember
your theory.  (I don't mean that's surprising or a problem, of

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