The use of serialization in PHP

<?
	/*
		作者 : shyhero
		邮箱 : shyhero@
		Q  Q : 1757424878

	 */
	class Person{				//声明一个Person类
		public $age;
		private $name;
		protected $sex;

		public function __construct($age="",$name="",$sex=""){
			$this -> age = $age;
			$this -> name = $name;
			$this -> sex = $sex;
		}

		public function say(){
			return $this -> age." ".$this -> name." ".$this -> sex;
		}

		function __sleep(){		//指定串行化时能提取的成员属性,没有参数,但是必须返回一个数组
			$arr = array("age","name");
			return $arr;
		}

		function __wakeup(){	//指定反串行化时,提取出来的值
			$this -> sex = "woman";
		}
	}