Final Access Control Modifier

Final

The final keyword is used to declare that a method or class cannot be overridden by a subclass. For example:

class A {
            private $Name;
            private $ATag;
            final public function say( ) {
                    print "Hello!\n";
            }
            // Statement here.

The A say( ) method is now declared final, which means it cannot be overridden in a child class. If we have say( ) redefined in the B class, PHP outputs a fatal error message: "Cannot override final method A::say( )". Using the final keyword is optional, but it makes your life easier by acting as a safeguard against people overriding a method you believe should be permanent.

For stronger protection, the 'final' keyword can also be used to declare a class uninheritable that is, that programmers cannot extend another class from it. For example:

Ex. --> final class A {
            private $Name;
            public function getName( ) {
                    return $this->Name;
            }
    }

    class B extends A {
            public function say( ) {
                    print "'Hello', says " . $this->getName( );
            }
    }

Attempting to run that script will result in a fatal error, with the message: "Class B may not inherit from final class (A)".