In cases in which you wish to prevent a subclass from overriding a superclass method, you can use the final keyword. Following Example shows how.

<?php
<?php
$object = new Subscriber;
$object->display1(); // calling override method
class User
{
    final function display1() // with final keyword
    {
        echo "not allowed";
    }
}
class Subscriber extends User // extending class
{
    function display1() // overriding function save_user
    {
		echo "this is not allowed"; 
    }
}
?>