PHP魔术方法之__get()和__set()方法

看代码：

<?php
class stu{
    private $a;
    private $b = 0;
    public $c;
    public $d = 0;
    
    public function __get($name) {
        return 123;
    }
     
    public function __set($name, $value) {
        echo "This is set function";
    }
}
 
$s = new stu();
 
var_dump($s->a);  //output: 123
var_dump($s->b);  //output: 123
var_dump($s->c);  //output: null
var_dump($s->d);  //output: 0
var_dump($s->e);  //output: 123
 
$s->a = 3;   //output: This is set function
$s->c = 3;  //no output
$s->f = 3;  //output: This is set function
?>

当你取值时，如果类中不存在这个属性或者是private的，对这个属性取值时，$object->e,就会自动调用__get()方法.当对这个属性赋值时就调用__set()方法。