https://note.com/kitoko552/n/nd25e46daf2d4

note_nd25e46daf2d4_4.dart

class Handler {
  Handler({
    this.increment,
  });

  final VoidCallback increment;
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: StoreProvider(
        store: Store<AppState>(
          reducer,
          initialState: AppState.init(),
        ),
        child: Provider(
          create: (context) {
            return Handler(
              increment: () {
                final store = StoreProvider.of<AppState>(context);
                store.dispatch(UpdateCount(store.state.count + 1));
              },
            );
          },
          child: const MyHomePage(),
        ),
      ),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    final handler = Provider.of<Handler>(context, listen: false);
    return Scaffold(
      appBar: AppBar(
        title: Text('Demo'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have pushed the button this many times:'),
            StoreConnector<AppState, int>(
              distinct: true,
              converter: (store) => store.state.count,
              builder: (context, count) {
                return Text(
                  '$count',
                  style: Theme.of(context).textTheme.display1,
                );
              },
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: handler.increment,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}