php笔记（10）——面向对象之魔术方法

朱雀 2022-08-22 13:26 220阅读 0赞

*  \_\_tostring
 *  \_\_invoke
 *  \_\_call
 *  \_\_staticcall
 *  \_\_get
 *  \_\_set
 *  \_\_isset
 *  \_\_unset
 *  \_\_clone

# `__tostring()` #

当对象被当作字符串输出时，调用该方法。

class People{ 
        public function __tostring(){ 
            return 'this is a people';
        }
    
    }
    
    $p1 = new People();
    echo $p1;

# `__invoke` #

当对象被当作方法调用时，会调用该方法

class People{ 
        public function __invoke($x){ 
            echo 'invoke..'.$x;
        }
    
    }
    $p1 = new People();
    $p1(1);

# `__call()` #

当访问对象的方法不存在时，将会调用该方法

class People{ 
        public function __call($name,$arguments){ 
            echo 'call..'.$name.' with args '.implode(',',$arguments);
        }
    
    }
    $p1 = new People();
    $p1->hehe('2','1');

# `__staticcall()` #

当访问类静态方法不存在时，调用该方法

class People{ 
        public static function __callStatic($name,$arguments){ 
            echo 'calling static function '.$name.' with args '.implode(',',$arguments);
        }
    
    }
    People::hehe('1','2');

# `__get()` #

当访问的属性不能正常访问时（没有该属性或者是private属性），调用该方法

class People{ 
        public  function __get($name){ 
            return "try to get property：".$name;
        }
    
    }
    $obj = new People();
    echo $obj->name;

# `__set()` #

当要赋值的属性不能正常访问时（没有该属性或者是private属性），调用该方法

class People{ 
        public  function __set($name,$value){ 
            echo "try to set property：".$name ." with value:".$value;
        }
    }
    $obj = new People();
     $obj->name = '11';

# `__isset()` #

当不可访问属性调用`isset()和empty()` 方法时，将会调用。

class People{ 
        public  function __isset($name){ 
            echo "calling isset ".$name ;
            return true;//return false;
        }
    }
    $obj = new People();
    isset($obj->name);

class People{ 
        public  function __isset($name){ 
            echo "calling isset ".$name ;
            return true;//return false;
        }
    
    }
    $obj = new People();
    empty($obj->name);

# `__unset()` #

当不可访问属性调用`unset()` 方法时，将会调用。

class People{ 
        public  function __unset($name){ 
            echo "calling unset ".$name ;
            return true;//return false;
        }
    
    }
    $obj = new People();
    unset($obj->name);

# `__clone()` #

如下的代码，如果直接使用赋值符号，那么两个变量p1和p2其实是指向同一个对象，如果修改p2，那么p1也会被修改

class People{ 
        public $name;
    
    }
    $p1 = new People();
    $p1->name = "name1";
    
    $p2 = $p1;
    $p2->name = "name2";
    
    echo "p1's name:".$p1->name.'<br>';
    echo "p2's name:".$p2->name;

![这里写图片描述][20160529172028190]

我们可以使用clone关键字，复制一个对象（内存中重新开辟一个空间）

class People{ 
        public $name;
    
    }
    $p1 = new People();
    $p1->name = "name1";
    
    $p2 = clone $p1;
    $p2->name = "name2";
    
    echo "p1's name:".$p1->name.'<br>';
    echo "p2's name:".$p2->name;

![这里写图片描述][20160529172208111]

在使用clone的时候，就会调用`__clone()`方法

class People{ 
        public $name;
    
        function __clone(){ 
            echo "calling clone<br>";
            //可以在此处修改克隆后的值
            $this->name = '111';
        }
    
    }
    $p1 = new People();
    $p1->name = "name1";
    
    $p2 = clone $p1;
    
    echo "p1's name:".$p1->name.'<br>';
    echo "p2's name:".$p2->name;

[20160529172028190]: /images/20220722/f0bd2152afd146d682a92e3ced82fce0.png
[20160529172208111]: /images/20220722/3b065f32ef2a4795b555f82989f5cac5.png