polymorphic.php

<?

interface Sortable {
   public function sort();
}

class Array implements Sortable {
   public function sort() {
      // Implementation of the sort() method for Array
   }
}

class List implements Sortable {
   public function sort() {
      // Implementation of the sort() method for List
   }
}

class Stack implements Sortable {
   public function sort() {
      // Implementation of the sort() method for Stack
   }
}