Event dispatcher

index.php

<?php

class Event
{

    public static $events;

    public function __construct()
    {
        self::$events = [];
    }

    public static function listen($name, $callback, $prio = 0)
    {
        self::$events[$name][$prio][] = $callback;
    }

    public static function sort($name = null)
    {
        $sorts;
        if ($name !== null)
        {
            $sorts = self::$events[$name];
            krsort($sorts);
        }
        else
        {
            foreach (self::$events as $events)
            {
                arsort($events);
                $sorts[] = $events;
            }
        }

        return $sorts;
    }

    public function dispatch($name = null)
    {
        $events = self::sort($name);
        foreach ($events as $key => $value)
        {
            foreach ($value as $callback)
            {
                $callback();
            }
        }
    }

}

Event::listen('name', function () {
    echo 1 . "\n";
}, 1);

Event::listen('name', function () {
    echo 2 . "\n";
}, 0);

Event::listen('name', function () {
    echo 3 . "\n";
}, 3);

Event::dispatch('name');