/** *单例模式示例 */final class Sigle{  private static $ins = null;  public static function getIns(){    if(self::$ins === null){      self::$ins = new self();    }    return self::$ins;  }  /**   * 封锁重写和继承   */  final private function __construct(){  }  /**   * 封锁克隆   */  final private function __clone(){  }}$s1 = Sigle::getIns();$s2 = Sigle::getIns();if($s1===$s2){    echo '是同一个对象';}else{    echo '不是同一个对象';}