如何从其他类外部加载类函数

class test {
    function callback(){
        echo "Test okay ";
    }   
}


class classload{
    var $class_instance;
    function __construct(){
        spl_autoload_register (array( $this , 'library' ));
    }

    public function __call ($fn , array $args ){
      if(isset( $this ->{ $fn })){
          array_unshift( $args , $this );
          call_user_func_array ( $this ->{ $fn }, $args );
      }
    }

    function library($class){
        $this->{$class} = new $class($this);
        //$this->class_instance = ${$class};
        return $this;
    }
}


 class classtwo {
     protected  $load;
    function __construct(){
        $this->load = new classload(); 
    }
}

class Classone extends classtwo {
    function view(){
        //load and initialise class
        $this->load->library('test');

      //  print_r($this->load->library('test'));
        echo $this->test->callback();
    }
}

  $init = new classone();
  echo $init->view();

return error undefined property classone::$test

and also call object ->callback() on null

I have tried to change object into variable but am still getting this error.