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

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karl williamson
August 2, 2010 18:10
Re: qr stringification: why are xism always present? I'm worriedabout backward compatibility
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Ævar Arnfjörð Bjarmason wrote:
> 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
> them.

Ah!  I see it also includes op.h, and I was hoping to get rid of the 
flags like PMf_LOCALE which are just duplicates of the RXf_ ones.  I 
think I can do that by changing ppport.h, or however it is generated. 
Do I need to worry about the defsubs.h exporting them, or is it really 
just used by B, and hence under our control.

> 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
> 5.12.
> 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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