找到目录，我的扩展类是与php

假设我们有一个dir

script.php是一个从index.php扩展的控制器类，

application/helloworld/script.php
index.php

是否有办法从index.php(控制器)返回文件夹helloworld ?

script.php

class Helloworld extends Controller
{
    function __construct()
    {
        echo 'helloworld';  
    }
}

index . php

class Controller
{
    function wherethescript(){
        # trying to find folder where helloworld.php is in from this class
    }
}
include_once 'application/helloworld/helloworld.php';
$x=new Helloworld;
$x->wherethescript();