#!/usr/bin/perl

use strict;
use warnings;

package Class;

sub foo {"Hello, world"}

package Evil;

sub foo {"All your base are belong to us"}

package main;

sub Class {"Evil"}
sub bar1  {Class->foo}
sub bar2  {+Class->foo}
sub bar3  {"Class"->foo}

print bar1, "\n";
print bar2, "\n";
print bar3, "\n";

__END__
All your base are belong to us
All your base are belong to us
Hello, world