QUIZGUM

Coding Class

Quizgum : Prevent class inheritance

Prevent Extends

In the previous section, we learned how to disable overriding. I used the final keyword before the accessor of the method that would prevent overriding Using final when declaring a class prevents inheritance.

How to use final in a class

  1. final class class name{}

So let's look at an example.

  1. <?php
  2.  
  3.     final class GoogleCar
  4.     {
  5.  
  6.     }
  7.  
  8.     class Car extends GoogleCar
  9.     {
  10.         public function hello()
  11.         {
  12.             return 'hello';
  13.         }
  14.     }
  15.     $ever = new Car;
  16.     echo $ever->hello();
  17.  
  18. ?>

The code above does not allow you to inherit GoogleCar using final.
But Car class is inheriting.
So I get an error
Result of the code above

Result

Clearing final in the code above allows inheritance, so no error occurs.

  1. <?php
  2.  
  3.     class GoogleCar
  4.     {
  5.  
  6.     }
  7.  
  8.     class Car extends GoogleCar
  9.     {
  10.         public function hello()
  11.         {
  12.             return 'hello';
  13.         }
  14.     }
  15.     $ever = new Car;
  16.     echo $ever->hello();
  17.  
  18. ?>

Result

Thank you.