php魔术方法

1. __construct  构造方法

   class Person
   {
       public $name;
   
       # 构造方法
       public function __construct($n){
           $this->name = $n;
       }
   
       public function say(){
           return "my name is {$this->name}";
       }
   }
   
   $obj = new Person('yach');
   echo $obj->say();

    

2. __destruct  析构方法

   public function __destruct(){
       echo "<p>{$this->name}被清理</p>";
   }
   
   # 后进先出 (弹夹原理)

    

3. __toString  对象说明

   class Usb
   {
       public function load(){
           echo "<p>load</p>";
       }
   
       public function __toString(){
           return 'This is a obj';
       }
   }
   
   $obj = new Usb();
   echo $obj;

    

4. __call  访问对象不存在的方法时调用

   class Usb
   {
       public function load(){
           echo "<p>load</p>";
       }
   
       public function __call($i,$j){
           return "<p>您访问的方法<b>{$i}</b>不存在</p>";
       }
   }
   
   $obj = new Usb();
   echo $obj->start();

    

5. __get  提示无权限获取的方法

   class Usb
   {
       private function load(){
           echo "<p>load</p>";
       }
   
       public function __get($i){
           return "<p>您无权访问{$i}方法</p>";
       }
   }
   
   $obj = new Usb();
   echo $obj->load;

    

6. __set  提示无权限设置的方法

   class Usb
   {
       private $name = 'yu';
   
       public function __set($i,$j){
           echo "<p>您无权设置{$i}为{$j}</p>";
       }
   }
   
   $obj = new Usb();
   $obj->name = 'yach';

    

7. __isset  检测私有属性值是否被设定

   class Usb
   {
       private $name = 'yu';
   
       public function __isset($i){
           return "<p>未设定{$i}属性</p>";
       }
   }
   
   $obj = new Usb();
   $b = isset($obj->name);
   echo $b;

    

8. __unset  无权删除提示

   class Usb
   {
       private $name = 'yu';
   
       public function __unset($i){
           echo "<p>您无权删除{$i}属性</p>";
       }
   }
   
   $obj = new Usb();
   unset($obj->name);