bloc_plus #

bloc_plus extends flutter_bloc with ergonomic widgets, null-safe context extensions, and reusable rebuild/listen policies.

Features #

• BlocBuilderWithBloc, BlocListenerWithBloc, BlocConsumerWithBloc, BlocSelectorWithBloc
• BuildContext extensions:
  • readOrNull<B>()
  • watchOrNull<B>()
  • selectOrNull<B, S, T>(selector)
  • withBloc<B, R>(fn)
• Reusable policies:
  • Rebuild: distinct, onChange, always, never
  • Listen: distinctListen, onChangeListen, alwaysListen, neverListen
• Async safety:
  • SafeEmitMixin
  • CancellationToken
  • RestartableTask
• Effects:
  • HasEffects
  • EffectListener

Getting started #

Add dependency:

dependencies:
  bloc_plus: ^0.1.1

Run the example app:

cd example
flutter pub get
flutter run

Usage #

UI widgets with bloc in callback #

class CounterView extends StatelessWidget {
  const CounterView({super.key});

  @override
  Widget build(BuildContext context) {
    return BlocBuilderWithBloc<CounterCubit, int>(
      builder: (context, bloc, state) {
        return Text('$state');
      },
    );
  }
}

Null-safe context access #

void tryIncrement(BuildContext context) {
  final counterCubit = context.readOrNull<CounterCubit>();
  counterCubit?.increment();
}

Policies #

class PolicyView extends StatelessWidget {
  const PolicyView({super.key});

  @override
  Widget build(BuildContext context) {
    final rebuildPolicy = onChange<MyState, int>((s) => s.count);
    final listenPolicy = onChangeListen<MyState, bool>((s) => s.isLoading);

    return BlocListenerWithBloc<MyCubit, MyState>(
      listenWhen: listenPolicy.shouldListen,
      listener: (context, bloc, state) {},
      child: BlocBuilderWithBloc<MyCubit, MyState>(
        buildWhen: rebuildPolicy.shouldRebuild,
        builder: (context, bloc, state) => Text('${state.count}'),
      ),
    );
  }
}

Async safety #

class MyCubit extends Cubit<int> with SafeEmitMixin<int> {
  MyCubit() : super(0);

  Future<void> load() async {
    final value = await guarded(() async => 1);
    if (value != null) safeEmit(value);
  }
}

Effects #

class AuthCubit extends Cubit<int> with HasEffects<int, String> {
  AuthCubit() : super(0);
}

class AuthEffectsView extends StatelessWidget {
  const AuthEffectsView({super.key});

  @override
  Widget build(BuildContext context) {
    return EffectListener<AuthCubit, int, String>(
      onEffect: (context, effect) {},
      child: const SizedBox.shrink(),
    );
  }
}