PubSub pattern / Events in PHP

## pub-sub.php
<?php

// more: http://baylorrae.com/php-pubsub/

class PubSub
{

	private static $events = array(); // all subscriptions

	// Don't allow PubSub to be initialized outside this class
	private function __construct() { }
	private function __clone() { }

	/**
	 * Adds a subscription to the stack
	 *
	 * @param string   $name
	 * @param function $callback needs to be callable with call_user_func()
	 * @return void
	 * @author Baylor Rae'
	 */
	public static function subscribe( $name, $callback )
	{

		// Make sure the subscription isn't null
		if ( empty( self::$events[ $name ] ) )
			self::$events[ $name ] = array();

		// push the $callback onto the subscription stack
		array_push( self::$events[ $name ], $callback );
	}

	/**
	 * Calls the last subscription in the stack
	 *
	 * @param string $name
	 * @param string $params
	 * @return false if fails
	 * @author Baylor Rae'
	 */
	public static function publish( $name, $params = '' )
	{

		// Check to see if the subscribe isn't null
		if ( empty( self::$events[ $name ] ) )
			return false;

		// Gets all parameters passed to the function
		// and removes the first, which is $name
		$params = func_get_args();
		array_shift( $params );

		// If there's only one event, then call it and return the value
		if ( count( self::$events[ $name ] ) === 1 )
		{
			if ( is_callable( self::$events[ $name ][ 0 ] ) )
				return call_user_func_array( self::$events[ $name ][ 0 ], $params );
			else
				return false;
		}

		// Loop through all the events and call them
		foreach ( self::$events[ $name ] as $event )
		{
			if ( is_callable( $event ) )
				call_user_func_array( $event, $params );
		}
	}

	public static function unsubscribe( $name )
	{
		if ( !empty( self::$events[ $name ] ) )
			unset( self::$events[ $name ] );
	}

}

// Basic usage
PubSub::subscribe( 'beforeSave', function ()
{
	echo 'PubSub::beforeSave';
} );

PubSub::subscribe( 'afterSave', function ()
{
	echo 'PubSub::afterSave';
} );

PubSub::publish( 'beforeSave' );

PubSub::unsubscribe( 'beforeSave' );