Re^2: why need my in a foreach loop?

[7stud]

in reply to Re: why need my in a foreach loop?
in thread why need my in a foreach loop?

Here's the difference:

use strict;
use warnings;
use 5.010;

our $foo = 'hello';

sub f {
   print("$foo\n");
}

for my $foo (qw( a b c )) {
   f();  
}

--output:--
hello
hello
hello

In ikegami's example, the my is omitted in the for loop, which causes the for loop to change the global variable $foo--and the subroutine prints the global $foo (i.e. the subroutine is a closure).

[ikegami]

the subroutine is a closure

Backwards. It works because the subroutine doesn't capture package variables. If you switched our for my in my snippet, you'd have a closure, and you'd get a different result.

[7stud]

Nice catch.

If you switched our for my in my snippet, you'd have a closure, and you'd get a different result.

Is that correct? Because the my variable would still be in scope, would the subroutine qualify as a closure? It's my understanding that a subroutine is a closure when it preserves a variable that has gone out of scope.

[ikegami]

I don't know the precise definition if there is one. For practical purposes, I find it doesn't matter.

Correction: In this case, the sub truly acts as a closure. If it didn't, it wouldn't matter if you used our or my.