运行时发错，望高人指点，谢谢

final  class MyPc{
static $name="我的电脑";
    static  function power(){
echo  self::$name."电脑开中...";
    }
}
MyPc::$name="你的电脑哦";
echo  MyPc::power()
  final  class My1{
const NAME="我的电脑";
    static  function power1(){
echo  My1::NAME."电脑开中...";
    }
}  My1::power1();