Final关键字

Final关键字

PHP 5 新增了一个 final 关键字。如果父类中的方法被声明为final，则子类无法覆盖该方法； 如果一个类被声明为final，则不能被继承。

Example #1 Final 方法示例

<?php
class BaseClass {
   public function test() {
       echo "BaseClass::test() called ";
   }
   
   final public function moreTesting() {
       echo "BaseClass::moreTesting() called ";
   }
}

class ChildClass extends BaseClass {
   public function moreTesting() {
       echo "ChildClass::moreTesting() called ";
   }
}
// 产生 Fatal error: Cannot override final method BaseClass::moreTesting()
?>

Example #2 Final 类示例

<?php
final class BaseClass {
   public function test() {
       echo "BaseClass::test() called ";
   }
   
   // 这里无论你是否将方法声明为final，都没有关系
   final public function moreTesting() {
       echo "BaseClass::moreTesting() called ";
   }
}

class ChildClass extends BaseClass {
}
// 产生 Fatal error: Class ChildClass may not inherit from final class (BaseClass)
?>