simplest Polymorphism example in Php

polymorphism.php

<?php
	  /* simplest Polymorphism example in Php */
	 abstract class Animal
	 {
		 static function makeSound(Animal $animal)
		 {
			 return $animal->getsound();
		 }
	 }
	 
	 class dog extends Animal
	 
	 {
	 	function getsound()
		{
			return "Woof Woof";
		}
	 
	 }
	 
	 class cat extends Animal
	  {
	 	function getsound()
		{
			return "Meow Meow";
		}
	 }
	 
	echo Animal::makeSound(new cat);
	echo Animal::makeSound(new dog);