Re: Accessing lexically scoped variables from a subref

ISBN 0596526741 Perl Hacks #76 recommends the use of PadWalker, such that you can write something like:

package Foo;

use PadWalker 'closed_over';

sub convert
{
    my ($package, $sub) = @_;
    my $vars            = closed_over( $sub );

    return join ', ', map { "$_ => $vars->{$_}" } keys %$vars;
}
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Comment on Re: Accessing lexically scoped variables from a subref Download Code

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Re^2: Accessing lexically scoped variables from a subref by /dev/urandom (Beadle) on Dec 28, 2007 at 01:26 UTC
This is indeed an excellent solution. The only problem is that it's not a pure perl module. However, after looking at the xs, the actual code for the closed_over function is rather small. For a simple subref: `$i = 12; $a = sub { $i };` [download] All it took to get $i was this: `B::svref_2object($a)->PADLIST->ARRAYelt(1)->ARRAYelt(1)->SV->object_2s +vref` [download] The only problem with using this is that I have no idea how it actually works. I just assumed that PADLIST contains all the local variables for that reference, but why the two-dimensional AV after that? Or for that matter, why is $i located on the second position of the second array? The others just return a B::SPECIAL, which I have no idea what its purpose is.	[reply] [d/l] [select]
Re: Accessing lexically scoped variables from a subref by benizi (Hermit) on Dec 31, 2007 at 04:41 UTC
The only problem with using this is that I have no idea how it actually works. I just assumed that PADLIST contains all the local variables for that reference, but why the two-dimensional AV after that? Short answer: the first array holds the names, the second holds the values. Longer answer: Read more... (3 kB)	[reply] [d/l] [select]


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