PubSub class for PHP

PubSub.php

<?php

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]);
  }
  
}

if( basename(__FILE__) === 'pubsub.php' ) {
  // Basic usage
  PubSub::subscribe('beforeSave', function() {
    echo 'PubSub::beforeSave';
  });

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

  // PubSub::unsubscribe('beforeSave');

  PubSub::publish('beforeSave');
}

How to use?
For every subscribe , we need to call publish Manually ?

@feng-ming http://baylorrae.com/blog/2011/12/21/php-pubsub/