philiprehberger_event_bus

Typed event bus with Stream subscriptions, sticky events, event history, and scoped lifecycle

Requirements

• Dart >= 3.6

Installation

Add to your pubspec.yaml:

dependencies:
  philiprehberger_event_bus: ^0.4.0

Then run:

dart pub get

Usage

import 'package:philiprehberger_event_bus/philiprehberger_event_bus.dart';

final bus = EventBus();

Fire and Listen

bus.on<String>().listen((event) {
  print('Received: $event');
});

bus.fire('hello');

Typed Events

class UserLoggedIn {
  final String userId;
  UserLoggedIn(this.userId);
}

bus.on<UserLoggedIn>().listen((event) {
  print('User logged in: ${event.userId}');
});

bus.fire(UserLoggedIn('user-123'));

Sticky Events

Sticky events are stored and replayed to new subscribers:

bus.fireSticky(UserLoggedIn('user-456'));

// New listener immediately receives the last sticky event
bus.on<UserLoggedIn>().listen((event) {
  print('Got sticky: ${event.userId}');
});

// Retrieve the last sticky event directly
final last = bus.lastSticky<UserLoggedIn>();

// Clear when no longer needed
bus.clearSticky<UserLoggedIn>();

One-Time Listener

Listen for a single event and automatically unsubscribe:

final event = await bus.once<UserLoggedIn>();
print('Got one: ${event.userId}');

Event History

Store past events and replay them to new subscribers:

bus.enableHistory<String>(maxSize: 50);

bus.fire('first');
bus.fire('second');

// Retrieve stored events
print(bus.history<String>()); // ['first', 'second']

// New subscriber receives history then live events
bus.onWithHistory<String>().listen((event) {
  print(event); // 'first', 'second', then any new events
});

// Clear stored events but keep collecting
bus.clearHistory<String>();

// Stop collecting history entirely
bus.disableHistory<String>();

Wildcard Listener

Listen to all events regardless of type — useful for logging and debugging:

bus.onAny().listen((event) {
  print('Event fired: $event');
});

bus.fire('hello');
bus.fire(42);
// Prints: Event fired: hello
// Prints: Event fired: 42

Listener Introspection

Check whether the bus has active listeners:

print(bus.hasListeners); // false

final sub = bus.on<String>().listen((_) {});
print(bus.hasListeners);  // true
print(bus.listenerCount); // 1

sub.cancel();
print(bus.listenerCount); // 0

Dispose

bus.dispose();

After calling dispose(), no more events can be fired or received.

API

Method	Description
fire<T>(T event)	Dispatch an event to all listeners of type T
on<T>()	Subscribe to events of type T, returns Stream<T>
onAny()	Subscribe to all events regardless of type, returns Stream<dynamic>
once<T>()	Returns a Future<T> that completes with the next event, then auto-cancels
fireSticky<T>(T event)	Dispatch a sticky event that replays to new subscribers
lastSticky<T>()	Get the last sticky event of type T, or null
clearSticky<T>()	Remove the stored sticky event of type T
enableHistory<T>({int maxSize})	Enable event history for type T with a max capacity
history<T>()	Get stored events of type T as an unmodifiable list
onWithHistory<T>()	Stream that emits stored history first, then live events
clearHistory<T>()	Clear stored events of type T without disabling collection
disableHistory<T>()	Stop collecting history for type T and discard stored events
hasListeners	Whether any listeners are currently active
listenerCount	Number of active stream subscriptions
dispose()	Close the bus and release all resources

Development

dart pub get
dart analyze --fatal-infos
dart test

Support

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License

MIT