<?php
class DanLi{
//靜態成員變量
private static $_instance;
//私有的構造方法
private function __construct(){
}
//防止對象被克隆
public function __clone(){
trigger_error('Clone is not allow!',E_USER_ERROR);
}
public static function getInstance(){
if(!(self::$_instance instanceof self)){
self::$_instance = new self;
}
return self::$_instance;
}
public function test(){
echo "ok";
}
}

//錯誤：$danli = new DanLi(); $danli_clone = clone $danli;
//正確：$danli = DanLi::getInstance(); $danli->test();

?>