What is Final Keyword in PHP ?

Sudheesh.R

PHP 5 introduces the final keyword, which prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.

Final methods example
<?php

class BaseClass {
public function test() {
echo “BaseClass::test() called\n”;
}

final public function moreTesting() {
echo “BaseClass::moreTesting() called\n”;
}
}

class ChildClass extends BaseClass {
public function moreTesting() {
echo “ChildClass::moreTesting() called\n”;
}
}

?>

OUTPUT :
Results in Fatal error: Cannot override final method BaseClass::moreTesting()

Final class example
<?php

final class BaseClass {
public function test() {
echo “BaseClass::test() called\n”;
}

// Here it doesn’t matter if you specify the function as final or not
final public function moreTesting() {
echo “BaseClass::moreTesting() called\n”;
}
}

class ChildClass extends BaseClass {
}

?>

OUTPUT :
Results in Fatal error: Class ChildClass may not inherit from final class (BaseClass)