bus 0.0.11

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Event Bus on Dart #

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

Functionality for JavaScript through dart2js is thanks to dart-patch-mirrors which provides some fixes for the buggy mirror functionality. All the examples provided work with dart2js.


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';

main() async {
  var bus = new Bus<String>();

  var sub = bus.subscribe((String message) {
    print('Received a string: "$message"');

  await bus.post('Hey there!');
  // cancel the subscription
  // the subscription was cancelled, this is pointless
  bus.post('This message will not be heard...');

Also supported is subscribing an object full of handlers:

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

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


var bus = new Bus<GameEvent>();
var subs = bus.subscribeAll(new GameListener()); // returns a list of subscriptions

// remember to cancel your event subscriptions
subs.forEach((s) => s.cancel());

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.

Changelog #

0.0.10 #

  • Remove Listener.

0.0.8 #

  • Add tests (sync, async and listeners tests).

0.0.7 #

  • Getter for message type
  • Internal changes, util file for helpers

0.0.5 #

  • Synchronous bus, via new SyncBus<T>().

0.0.2-0.0.4 #

  • Documentation, README fixes.

0.0.1 #

  • Initial beta version.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:

  bus: ^0.0.11

2. Install it

You can install packages from the command line:

with pub:

$ pub get

Alternatively, your editor might support pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:

import 'package:bus/bus.dart';
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The package version is not analyzed, because it does not support Dart 2. Until this is resolved, the package will receive a health and maintenance score of 0.

Analysis issues and suggestions

Support Dart 2 in pubspec.yaml.

The SDK constraint in pubspec.yaml doesn't allow the Dart 2.0.0 release. For information about upgrading it to be Dart 2 compatible, please see https://dart.dev/dart-2#migration.

Maintenance issues and suggestions

Make sure dartdoc successfully runs on your package's source files. (-10 points)

Dependencies were not resolved.


Package Constraint Resolved Available
Direct dependencies
Dart SDK >=1.20.1 <2.0.0