bus 0.0.8

A light-weight event bus implementing the pub-sub pattern.

Event Bus on Dart

A light-weight event bus library for Dart implementing the pub-sub pattern.

Send a message to the bus and let the bus distribute the message to various handlers which are subscribed to that type of event. This library utilizes the Stream async library in Dart to handle subscriptions and publishing messages.

Install

See pub.dartlang.org for instructions on how to use bus in your project.

Usage

A simple usage example:

import 'package:bus/bus.dart';

class Event {
  final DateTime timestamp;

  Event() : this.timestamp = new DateTime.now();
}

main() async {
  // Create a new bus, which accepts messages of type Event.
  var bus = new Bus<Event>();

  // Subscribe a single handler
  bus.subscribe((Event event) {
    print('An event occurred at ${event.timestamp}.');
  });

  // Post the event and (optional) await for handlers to receive them 
  await bus.post(new Event());
}

Also supported is subscribing an object full of handlers:

class GameListener implements Listener {
  @handler
  _onGame(GameEvent event) {
    print('[An event occurred at ${event.timestamp}]');
  }

  @handler
  _onChat(ChatEvent event) {
    print('${event.username} says "${event.message}"');
  }
}

...

bus.subscribeAll(new GameListener());

See the game example for explicit details.

For your synchronous needs, you can use SyncBus to publish and handle messages synchronously.

Features and bugs

Please file feature requests and bugs at the issue tracker.