Hi monks!

I've run into an interesting problem with closures. Here's my minimal test case: 

use strict;
use warnings;

sub run_this { shift->() }

{
  my $x = "hello\n";

  sub foo {
#    print $x;
    run_this(sub {
      print $x;
    });
  }
}

foo();

[download]
This compiles just fine, but if you run it $x doesn't print and an "uninitialized value" warning is generated. However, if you uncomment the first "print" statement, it works! $x is printed correctly both times.

Edit: turns out to be a bug in perl, fixed in 5.9.3. Thanks monks!

My best guess is that perl thinks that $x is not used within foo(), so it doesn't bother to keep track of it -- unless you reference $x directly within foo(). Maybe it doesn't look into the inner sub or something.

In any case, it seems to me that perl should either complain about $x in the anonymous sub at compile time, or it should just work. But I may be completely off track here.

Any ideas? Thanks!
asokoloski

In reply to Doubly-nested deeply bound variable is undefined by asokoloski

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