PHP全局变量在spl_autoload_register中返回未定义

Question

这是我真正的短代码，以某种方式让我头疼。

<?php 


$folders = ["","Models","Database","Pages"];
function foldersConcat($folder){
    array_push($folders,$folder);
}
try {
    spl_autoload_register(function ($classname){
        foreach ($folders as $path) { //getting undefined variable folders
            require ucfirst($path)."/".$classname.".php";
        }
    });

} catch (\Throwable $th) {
}

感谢您的帮助。