Re^5: Lexical closures

[ig]

Using my on for/foreach loop variables is not merely making explicit the implicit localization that is provided by the loop: the new lexical variable is distinct from any variable of the same name (lexical or not) in the surrounding scope.

Note the difference in the following example:

#!/usr/bin/perl
use strict;
use warnings;

use vars qw($n);

$n = "global";

sub foo {
        my $x = shift;
        print "$x, $n\n";
}


foreach $n (0..2) {
        foo($n);
}

print "\$n = $n\n";

foreach my $n (0..2) {
        foo($n);
}

print "\$n = $n\n";

Which produces:

0, 0
1, 1
2, 2
$n = global
0, global
1, global
2, global
$n = global

After both foreach loops the global $n remains unchanged but within the first (my not used) the global is affected while within the second (my is used) the global is not affected.