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Re: qr stringification: why are xism always present? I'm worried about backward compatibility

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Ævar Arnfjörð Bjarmason
August 2, 2010 17:53
Re: qr stringification: why are xism always present? I'm worried about backward compatibility
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On Tue, Aug 3, 2010 at 00:09, karl williamson <> wrote:

> But I do have a related implementation question.  perlreapi.pod describes
> how one can plug-in another regex handler.  I believe that 'use re debug' is
> such a plug-in.  What I don't see is how the writer of some other similar
> plug-in gets access to the various flag #defines, such as RXf_PMf_LOCALE,
> which is listed in the pod.  I've scanned the XS documentation, and don't
> see how such a module gets access to the flag #defines used in a general
> function.  Can they use any perl header?  If so, we have lots more backward
> compatibility worries than I thought. The only place that I see some of
> these exported is in defsubs.h, but I think that is only for the B module,
> but I'm pretty clueless about that whole area of Perl.  Any answers, advice
> or documentation pointers would be appreciated.

Yes, the RXf_PMf_* flags are available to everyone. They're in
regexp.h which is used by perl.h. So every XS extension has access to

This isn't something you should worry about a lot though. The regexp
interface is still experimental, and existing modules broke completely
in 5.12. Most of the re::engine::* stuff on CPAN doesn't work with
5.12, although Vincent made re::engine::Plugin work on both 5.10 and

The perlreapi.pod still documents the API as it was in 5.10 though, it
wasn't updated for those 5.10 -> 5.12 changes.

The RXf_PMf_* flags also used to be called just RXf_* until late 2006
when Yves changed them in bbe252da68.

You might have to worry about a lot of stuff when getting this patch
through, breaking the regex "API" isn't one of them.

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