in reply to why need my in a foreach loop?

When using strict perl requires to declare even the loop variable of a foreach loop.

It can use package variables, for starters. 

our $foo;

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

for $foo (qw( a b c )) {
   f();  # Prints a, b and c.
}

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Foreach loops existed long before "my".

Why is this code not allowed?

It generates an error for all instances of $word since you never declared it and you asked to make such things errors.

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Re^2: why need my in a foreach loop?
by 7stud (Deacon) on Nov 28, 2010 at 19:59 UTC

    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

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    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).

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[d/l]

      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.

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[d/l]
[select]

        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.
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