#!/usr/bin/perl

use strict;
no warnings;

use Scalar::Util qw/ dualvar /;

my $foo = dualvar 1, "foo";
my $bar = dualvar 2, "foo";

print "Using dualvar$/";
print '$foo', ($foo eq $bar ? " eq " : " ne "), '$bar', $/;
print '$foo', ($foo == $bar ? " == " : " != "), '$bar', $/;

__END__
Using dualvar
$foo eq $bar
$foo != $bar