final，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。
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 ";
}
}
// Results in Fatal error: Cannot override final method BaseClass::moreTesting()
?>