<?php     /**      * 针对类中的魔术方法 __isset() 和 __unset() 的例子      */ class Example {     public $public;     protected $protected;     private $private;         public function __construct(){         $this->public = 'pub';         $this->protected = 'pro';         $this->private = 'pri';     }         public function __isset($var){         echo '这里通过__isset()方法查看属性名为 '.$var."\n";     }         public function __unset($var){         echo '这里通过__unset()方法要销毁属性名为 '.$var."\n";     } } $exa = new Example; echo '<pre>'; var_dump(isset($exa->public)); echo "\n"; var_dump(isset($exa->protected)); echo "\n"; var_dump(isset($exa->private)); echo "\n"; var_dump(isset($exa->noVar)); echo "\n"; echo '<hr/>'; unset($exa->public); var_dump($exa); echo "\n"; unset($exa->protected); echo "\n"; unset($exa->private); echo "\n"; unset($exa->noVar); echo "\n";

object(Example)#1 (2) {   ["protected:protected"]=>   string(3) "pro"   ["private:private"]=>   string(3) "pri" }