Without Visual Debts (Not my opinion)

without-visual-debts.php

<?php

class Event {
  
    protected $events = [];
  
    function listen($name, $handler)
    {
        $this->events[$name][] = $handler;
    }
  
    function fire($name)
    {
        if (! array_key_exists($name, $this->events)) {
            return false;
        }
      
        foreach ($this->events[$name] as $event) {
            $event();
        }

        return true;
    }
}