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Postings from July 2019
"Paul \"LeoNerd\" Evans" <leonerd@leonerd.org.uk> writes:
> There's some handy macros in feature.h that define useful tests like
>
> if (!FEATURE_SIGNATURES_IS_ENABLED)
> Perl_croak(aTHX_ "Experimental subroutine signatures not enabled");
>
> If I do something like this then I can use them in an XS module:
>
> #define PERL_EXT
> #include "feature.h"
>
> Is that a good idea?
PERL_EXT is for core extensions (XS modules under ext/), so doing that
is almost as naughty as defining PERL_CORE in a CPAN module (which is
more common on CPAN¹). However, since you're only doing this for
already-released versions, it's unlikely to break in practice.
[1]:
https://grep.cpanauthors.org/search?q=%22define+PERL_CORE%22&extension=xs&extension=h
https://grep.cpanauthors.org/search?q=%22define+PERL_EXT%22&extension=xs&extension=h
> If not, could it become one somehow? It'd be useful to have a nice way
> for XS modules (especially those implementing syntax features) to
> easily query such state. Without this I'd have to do quite a bit of
> copy-pasting from internals to get the same effect.
We have documented APIs for checking warning categories, both in XS
(https://perldoc.pl/perlapi#Warning-and-Dieing), and Perl
(https://perldoc.pl/warnings#Reporting-Warnings-from-a-Module), so I
don't see why features shouldn't have something equivalent.
Well volunteered (again)!
- ilmari, *g,d&r*
--
"I use RMS as a guide in the same way that a boat captain would use
a lighthouse. It's good to know where it is, but you generally
don't want to find yourself in the same spot." - Tollef Fog Heen
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