atom_event_bus

Description:

atom event bus

Atom Event Bus #
An Event Bus based on Publish/Subscribe pattern to decouple your code dependencies using dart's Stream.
Features #

A single event bus for an app instance.
Subscribe to any event anywhere
debounce and oneOff listeners
uses dart stream

Diagram #

Getting started #
dependencies:
flutter:
sdk: flutter

# other deps
atom_event_bus:
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Usage #

Create Events
Subscribe to Events by EventRule
Emit Event by EventBus.emit

Example #

// --------------------------- events.dart ---------------------------
final signInEvent = Event<bool>("SIGN_IN_EVENT");

// -------------------------- subscriber.dart -------------------------
class SignedInStatus extends StatefulWidget {
const SignedInStatus({Key? key}) : super(key: key);

@override
_SignedInStatusState createState() => _SignedInStatusState();
}

class _SignedInStatusState extends State<SignedInStatus> {
bool signedIn = false;
late EventRule signInRule;

@override
void initState() {
super.initState();

signInRule = EventRule<bool>(signInEvent, targets: [
EventListener(onSignInEvent),
]);
}

void onSignInEvent(bool status) {
setState(() {
signedIn = status;
});
}

@override
Widget build(BuildContext context) {
final theme = Theme.of(context).textTheme;

return Center(
child: Text(
"Is Signed In? \n${signedIn ? 'Yes' : 'No'}",
textAlign: TextAlign.center,
style: theme.headline1,
),
);
}

@override
void dispose() {
signInRule.cancel(); // cancelling the subscription
super.dispose();
}
}


// ----------------- emitter.dart -------------------
class ToggleSignInStatus extends StatelessWidget {
const ToggleSignInStatus({Key? key}) : super(key: key);

@override
Widget build(BuildContext context) {
return FloatingActionButton(
onPressed: () {
EventBus.emit(signInEvent.createPayload(true));
},
child: const Icon(Icons.replay_outlined),
);
}
}


// ------------- main.dart -------------
void main() {
runApp(const MyApp());
}

class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);

@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'ATOM EVENT BUS',
theme: ThemeData(
primarySwatch: Colors.green,
),
home: const MyHomePage(title: 'ATOM EVENT BUS'),
);
}
}

class MyHomePage extends StatelessWidget {
const MyHomePage({Key? key, required this.title}) : super(key: key);

final String title;

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
centerTitle: true,
),
body: const SignedInStatus(), // <-- subscribe to Events
floatingActionButton: const ToggleSignInStatus(), // <-- emit Events
);
}
}

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Listeners #

EventListener : normal event listener which get trigger for every event of corresponding event rule.
OneOffEventListener : event listener which get triggered only once.
DebouncedEventListener : event lister which prevent frequent events and only capture last event after a short delay.

Additional information #
Publish–subscribe_pattern : Wikipedia