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Postings from June 2008
2008/6/5 Yuval Kogman <nothingmuch@woobling.org>:
> It appears that ??{ } behaves like a closure only on it's first
> invocation, and not at the time that is actually
> compiled/encountered lexically:
>
> use Test::More 'no_plan';
>
> use re 'eval';
>
> {
> use re "eval";
>
> my $foo;
>
> my $bar = qr{ (a+) ((??{$foo})) }x;
>
> $foo = qr{ b+ }x;
>
> sub match {
> # uncommenting this retains $foo, and makes the tests pass
> #{ no warnings 'void'; $foo; } # force capture of interpolated lexical
> $_[0] =~ m{ $bar }x;
> return ($1, $2);
> }
>
> # uncommenting this also retains $foo
> #is_deeply([ match("aaabb") ], [qw(aaa bb)]);
> }
>
> is_deeply([ match("aaabb") ], [qw(aaa bb)]);
>
>
> This test fails because $foo is uninitialized in the execution of $bar.
>
> However, if $bar is executed once before $foo's scope is left then it will be
> retained, and likewise if the subroutine forces $foo to be captured then it is
> also retained, and the matching succeeds.
>
> I'm guessing this is a bug?
That's known. I think Dave has plans to fix that (but it won't be
completely trivial).
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