关于静态方法中不能使用$this

class Test{
   public $str;
    function __destruct()
   {
       // TODO: Implement __destruct() method.
       echo '销毁对象'.PHP_EOL;
       echo $this->str;
   }

   function __construct($v)
   {
       $this->str=$v;
       echo $this->str;
   }

}

$t = new Test('ccccccc');

输出
//ccccccc
//Warning: Call to private Test::__destruct() from context '' during shutdown ignored in Unknown on line 0
//PHP Warning:  Call to private Test::__destruct() from context '' during shutdown ignored in Unknown on line 0

// 课程中有讲$this在静态方法中不可用. 但是我在__destruct()加了关键字private 爆出警告信息 Warning: Call to private Test::__destruct()
// 那么构造函数也是一个静态方法了. 却是$this可以在里面使用的。