Code zum Video https://youtu.be/yJRTHI6EPuA

Event.php

<?php 
function event(string $name, array $data = [],callable $action = null,int $priority = 0){
    static $events = [];
    if($action){
        $events[$name][]=[
            'priority' => $priority,
            'action' => $action
        ];
        return null;
    }
    if(!isset($events[$name])){
        return null;
    }
    $eventData = $events[$name];
    
    usort($eventData,function($a,$b){
        return $b['priority'] <=> $a['priority'];
    });
    
    foreach($eventData as $event){
        $event['action'](...$data);
    }
    
    return null;
    
}