package Cow;

     sub new
     {
             my ($this) = shift;
             my ($class) = ref($this) || $this;
             my ($meat) = {};
             bless ($meat, $class);
             return $meat;
     }
 
     sub grind
     {
             my ($meat) = shift;
             bless ($meat, "Beef");
             return $meat;
     }

     package main;

     my ($bessie) = new Cow();

     grind $bessie;