Source code for: http://baylorrae.com/php-pubsub/

adding_subscriptions.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);
  }

}

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

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

concept.php

<?php

/*
    Somewhere in the core files
*/
PubSub::subscribe('beforeSaveRecord', function($record_data) {
    # code...
});

PubSub::subscribe('afterSaveRecord', function($record_data) {
    # code...
});

function save_record($record_data) {
    $record_data = PubSub::publish('beforeSaveRecord', $record_data);
    # code ...
    PubSub::publish('after_save_record', $record_data);
}

// my code
PubSub::subscribe('beforeSaveRecord', function($record_data) {
    # do stuff with $record_data
});

save_record(array(
    'username' => 'BaylorRae',
    'first_name' => 'Baylor',
    'last_name' => 'Rae\''
));

?>

problem.php

<?php

function before_save_record($record_data) {
    # code...
}

function after_save_record($record_data) {
    # code...
}

function save_record($record_data) {
    $record_data = before_save_record($record_data);
    # code ...
    after_save_record($record_data);
}

save_record(array(
    'username' => 'BaylorRae',
    'first_name' => 'Baylor',
    'last_name' => 'Rae\''
));

?>

publishing_subscriptions.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);
    }
  }

}

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

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

PubSub::publish('beforeSave');
?>

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]);
  }

}

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

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

PubSub::unsubscribe('beforeSave');

PubSub::publish('beforeSave');
?>

realistic_example.php

<?php

// user_manager.php from xxx.com
PubSub::subscribe('saveLogin', function($user_token) {
    $_SESSION['user_token'] = $user_token;
});

// my_file.php
PubSub::subcribe('saveLogin', function($user_token) {
    Cookie::set('user_token', '1 year', $user_token);
});

?>

result_1.php

Array
(
    [beforeSave] => Array
        (
            [0] => Closure Object
                (
                )

        )

    [afterSave] => Array
        (
            [0] => Closure Object
                (
                )

        )

)