juju-php/events.trait.php

<?php
	trait Events {
		private $events = [];
		public function on(string $name, Callable $fn){
			if(!isset($this->events[$name])){
				$this->events[$name] = [];
			}
			$this->events[$name][] = $fn;
			return $this;
		}
		public function off(string $name, Callable $fn = null){
			if(isset($this->events[$name])){
				$a = $this->events[$name];
				foreach($a as $k => $f){
					if(is_null($fn) || $f == $fn){
						array_splice($a, $k, 1);
					}
				}
			}
		}
		public function fire(string $name, ...$args){
			if(isset($this->events[$name])){
				foreach($this->events[$name] as $fn){
					$fn(...$args);
				}
			}
		}
	}
?>