event listener with priorities

listener_with_priorities.php

<?php

class Event
{
    public $priority;
    
    public $call;
    
    public $name;
    
    public function __construct(string $name, callable $call, int $priority = 0)
    {
        $this->name = $name;
        $this->call = $call;
        $this->priority = $priority;
    }
    
    public function execute($var)
    {
        $call = $this->call;
        
        if (is_callable($call)) {
            return $call($var);
        }
    }
}

class Listener
{
    protected $events = [];
    
    public function register(Event $event)
    {
        $this->events[] = $event;
        
        return $this;
    }
    
    /**
     * @return Event[]
     */ 
    public function getEvents()
    {
        $events = $this->events;
        
        usort($events, function ($a, $b) {
            return $a < $b; 
        });
        
        return $events;
    }
    
    public function run($var)
    {
        foreach($this->getEvents() as $event)
        {
            $event->execute($var);
        }
    }
}

$ev1 = new Event('a', function () {echo 'a';}, 2);
$ev2 = new Event('b', function () {echo 'b';}, 3);
$ev3 = new Event('3', function () {echo 'c';}, 1);

$l = new Listener();
$l->register($ev1);
$l->register($ev2);
$l->register($ev3);

$l->run(1);

// bac