#file state.pl
sub foo {
    my $bar if 0;
    $bar++;
    print "foo called $bar times\n";
}
foo for 'a'..'f';
__END__
Deprecated use of my() in false conditional at state.pl line 2.
foo called 1 times
foo called 2 times
foo called 3 times
foo called 4 times
foo called 5 times
foo called 6 times

##</code><code>##

# file state.pl
my $cond;
sub foo {
    my @bar if $cond;
    push @bar, @_;
    print "array \@bar = (@bar)\n";
}
foo $_ for 'a'..'f';
$cond = 1;
foo $_ for 1..6;
__END__
array @bar = (a)
array @bar = (a b)
array @bar = (a b c)
array @bar = (a b c d)
array @bar = (a b c d e)
array @bar = (a b c d e f)
array @bar = (a b c d e f 1)
array @bar = (2)
array @bar = (3)
array @bar = (4)
array @bar = (5)
array @bar = (6)

##</code><code>##

use feature qw(state);
# also
use 5.10.0;

sub foo {
    state @bar;
    ...
}