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Re: bug in elisp... or in elisper???


From: Stefan Monnier
Subject: Re: bug in elisp... or in elisper???
Date: Wed, 23 Mar 2011 11:27:34 -0400
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux)

> I am, however, starting to have trust issues with documentation I find
> on the web.

Don't believe everything you read.

> Is it actually true (what the docs say) that there's a limit of nine
> sub-expression match-strings per RE?

No.

> Or can I do, e.g., "(match-string 12)" and "(match-string 15)"?

Yes.

> What is the actual limit?

The limit currently is around 255 sub-groups (or maybe 127), IIRC.
OTOH back-references can only refer to subgroups 1-9 (because we
haven't bothered to introduce a syntax for other cases).

> Whatever it is, is this hard-coded into elisp... or can it be
> changed/configured to something else?

It's hardcoded in the C code of the regexp engine.

BTW, I recommend you use the "online" documentation distributed with
Emacs.  There are function and variable docstrings (C-h f, C-h v), plus
Info documents (Emacs manual, Elisp manual).  We work pretty hard to keep
those up-to-date and of good quality.  And if you find something to be
untrue in there, please report it via M-x report-emacs-bug.


        Stefan


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