<?php
   class ObjectTracker //对象跟踪器
   {
       private static $nextSerial = 0;
       private $id;
       private $name;

       function __construct($name) //构造函数
       {
           $this->name = $name;
           $this->id = ++self::$nextSerial;
       }

       function __clone()  //克隆
       {
           $this->name = "Clone of $that->name";
           $this->id = ++self::$nextSerial;
       }

       function getId() //获取id属性的值
       {
           return($this->id);
       }

       function getName() //获取name属性的值
       {
           return($this->name);
       }
   }

   $ot = new ObjectTracker("Zeev's Object");
   /*
    * $ot2 = $ot->__clone();
  这一行应当改为
  $ot2 = clone$ot;
    *
    */
   $ot2 = clone$ot;

   //输出: 1 Zeev's Object
   print($ot->getId() . " " . $ot->getName() . "<br>");

   //输出: 2 Clone of Zeev's Object
   print($ot2->getId() . " " . $ot2->getName() . "<br>");
?>