Hi, that is a very interesting use case, and IMO a very valid one.

Currently the semantics are, to also explain the correct syntax of the
pair that follows a 'use NAME':
:auth<Bar> and :ver<1.2> etc are of type Pair. Wenn the compiler hits a
use statement, it smartmatches
the distribution's auth/name/ver against the value of the corresponding

That means these Pairs are valid:

:auth<Bar> # match literally
:auth(/\w+/) # regex match
:auth($author) # okay if $author is known at compile time
:auth(*.chars == 6) # oaky, whatevercode
:auth({ $_.starts-with('Bla') }) # okay, closure
:auth(-> $auth { $auth ~~ /Bla/ }) # okay, something callable with arity
== 1
:auth({ $^auth ~~ /Bla/ }) # okay, something callable with arity == 1

That also means we cannot match different version patterns for different
:auth patterns, because we only
pass one value to the Pair's value to smartmatch against. What I can
imagine though is that if the matcher
is callable, and has an arity of 2, we pass the CompUnit as the first
and the $auth as the second argument.
That needs consensus in #perl6 though.

Cheers, Tobias

Am 11.06.2015 um 05:26 schrieb Darren Duncan:
> So I have a question about versioning, either/especially about
> compilation units, but also Perl 6 itself.
> For context I refer to http://design.perl6.org/S11.html#Versioning .
> With regard to "use" statements and specifying 'auth' or 'ver' to
> restrict between versions, it seems to me that the spec defines them
> interacting in a cross-product fashion.
> For example, given this possibly incorrect syntax:
>     use Dog:auth<cpan:TPF cpan:JRANDOM>:ver(4-6, 10-15);
> ... that would be satisfied by any of TPF versions 4-6,10-15 or
> JRANDOM versions 4-6,10-15.
> However, what I want is to restrict the 'ver' differently depending on
> the 'auth', treating them more as the hierarchy they are, assuming
> that different authorities may go off and use different versioning
> schemes.
> The question I have is how to 'or' the following into a single 'use
> Dog' that isn't any less restrictive:
>     use Dog:auth<cpan:TPF>:ver(v1.2.1..v1.2.3);
>     use Dog:auth<cpan:JRANDOM>:ver(v14.3..v16.2);
> That is, the cross-product answer is not restrictive enough.
> I don't know if this hypothetical use case has been discussed before,
> but if not, I hope that the Perl 6 specification has or can gain a
> clean way to say how its done.
> Thank you.
> -- Darren Duncan

Reply via email to