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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.

In reply to Re^5: Lexical closures by ig
in thread Lexical closures by spurperl

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