php 面向对象OOP, 单例模式

<?php
   //面向对象OOP
   class OOP{
      private $name = "wenhu"; //私有的
      protected $age = 24; //受保护的
      public static $_instance; //静态

      public function __set($p,$v){//私有属性设置
         if(property_exists($this, $p)){
            $this->$p = $v;
         }
      }

      public function __get($p){//私有属性访问
         if(property_exists($this, $p)){
            return $this->$p;
         }
      }

      private function __construct(){//构造函数

      }
      private function __clone(){//克隆方法

      }

      public function dome(){

      }

      public static function main($className){//静态函数
         if(self::$_instance == NULL){
            self::$_instance = new $className();
         }
         return self::$_instance;
      }

      private function __destruct(){//析构函数

      }

   }
?>