php_demo/07面向对象/18静态绑定.php

<?php
    //静态绑定前
    class ClassA{
        public function fnA(){
            echo __CLASS__.PHP_EOL;
        }

        public function fnB(){
            self::fnA();  //调用的是ClassA中的fnA
        }
    }

    class ClassB extends ClassA
    {
        public function fnA(){
            echo __CLASS__.PHP_EOL;
        }
    }

    ClassB::fnB();

    //后期静态绑定
    class ClassC{
        public function fnA(){
            echo __CLASS__.PHP_EOL;
        }
        
        public function fnB(){
            static::fnA(); //继承之后static代表的是ClassB
        }
    }

    class ClassD extends ClassC{
        public function fnA(){
            echo __CLASS__.PHP_EOL;
        }
    }

    ClassD::fnB();
?>