Front page | perl.perl5.porters |
Postings from December 2021
On Wed, 8 Dec 2021 21:18:30 +0000
Nicholas Clark <nick@ccl4.org> wrote:
> On Tue, Dec 07, 2021 at 06:02:23PM +0000, Paul "LeoNerd" Evans wrote:
>
> > I think a lot of that isn't even necessary though. A variant of my
> > no-snails branch which I haven't yet committed or pushed, very
> > slightly relaxes the rules and allows a use of @_ as an rvalue in
> > scalar context, purely to allow the code to determine the argument
> > count.
>
> > Potentially we could even still permit the use of @_ but only in
> > known-{scalar rvalue} contexts (such as the code above) allowing it
> > to continue to run unmodified from its current form. Already there
> > is lots of real code out in the wild (on CPAN and elsewhere) using
> > @_ in signatured subs in this way, and I think it would be nice not
> > to break them.
>
> This was my view too, for this reason.
>
> It's the wrong design if we started from a clean sheet, but we aren't.
>
> Effectively we're saying that (for a while yet) we'll permit `scalar
> @_` as a strange special way to write builtin::argc (or something
> like that, if it ever comes to exist)
>
> But discourage it for new code. And at some point deprecate it.
Latest copy of the code on the branch (force-pushed) now permits
scalar(@_) as a means to query the argcount:
$ ./perl -Ilib -Mfeature=signatures -E 'sub f(@args) { say "We have ", scalar(@_), " arguments" } f("a","b")'
The signatures feature is experimental at -e line 1.
We have 2 arguments
while still forbidding actual access as a real list/array, or elements
thereof. Also adds unit tests to this effect.
--
Paul "LeoNerd" Evans
leonerd@leonerd.org.uk | https://metacpan.org/author/PEVANS
http://www.leonerd.org.uk/ | https://www.tindie.com/stores/leonerd/
Thread Previous
|
Thread Next