Code zum Youtube Video https://youtu.be/wK6AVvO-rAI

autoload.php

<?php
$rootDir = __DIR__.'/classes/';

$autoload = function($className) use($rootDir){
   
    $fileName = '';
    if($lastNameSpacePosition = strpos($className,'\\')){
        $namespace = substr($className, 0,$lastNameSpacePosition);
        $className = substr($className,$lastNameSpacePosition+1);
        $fileName = str_replace('\\',DIRECTORY_SEPARATOR,$namespace).DIRECTORY_SEPARATOR;
    }
    $fileName .= str_replace('_', DIRECTORY_SEPARATOR, $className);
    if(is_file($rootDir.$fileName.'.php')){
    require_once $rootDir.$fileName.'.php';
    }
};

spl_autoload_register($autoload);