<?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";

bool(true)这里通过__isset()方法查看属性名为 protectedbool(false)这里通过__isset()方法查看属性名为 privatebool(false)这里通过__isset()方法查看属性名为 noVarbool(false)------------------------------------------------------------------------------object(Example)#1 (2) {  ["protected:protected"]=>  string(3) "pro"  ["private:private"]=>  string(3) "pri"}这里通过__unset()方法要销毁属性名为 protected这里通过__unset()方法要销毁属性名为 private这里通过__unset()方法要销毁属性名为 noVar