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Postings from February 2018
On Tue, Feb 20, 2018 at 10:35:06AM -0800, Father Chrysostomos via RT wrote:
> Specifically, how does one signal from a MODIFY_CODE_ATTRIBUTES sub that
> the attribute is going to install parsing hooks of some sort?
>
> I think the answer is that the module needs to be able (even at the XS
> level) to enquire as to whether the sub’s op-parsing has begun yet. Do
> we need a new API function for that?
My understanding of custom attributes is that they are all handled
*after* compilation of the sub is completed; i.e.
sub f :Foo(foo) :Bar(bar) { ....}
is compiled as
sub f { ....}
use attributes __PACKAGE__, \&f, 'Foo(foo)', 'Bar(bar)';
(with MODIFY_CODE_ATTRIBUTES() called by attributes->import()).
So it doesn't really matter whether the attribute appears before or after
the signature: these three:
sub f ($a) :Foo(foo) :Bar(bar) { ....}
sub f :Foo(foo) ($a) :Bar(bar) { ....}
sub f :Foo(foo) :Bar(bar) ($a) { ....}
all compile to the equivalent of:
sub f ($a) { ....}
use attributes __PACKAGE__, \&f, 'Foo(foo)', 'Bar(bar)';
and thus order is only important for builtin attributes.
(Or perhaps I'm misunderstanding something).
--
My get-up-and-go just got up and went.
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