To clarify...

$y = 123;
sub f { print("$y\n"); }  # 456 or 123
{ local $y = 456; f(); }  # Same var, localized
f();                      # same var, global
__END__
456
123
[download]

my $x = 123;
sub f { print("$x\n"); }  # 123
{ my $x = 456; f(); }     # Different var
f();
__END__
123
123
[download]

my vars are static, local vars are dynamic. Again - my/local, space/time (was: Re: The difference between my and local)