djinn_flutter 0.3.0

Application state management, using class inheritance to create services.

djinn_flutter

Djinn-state implementation for flutter.

The djinn-state is an application state management, using class inheritance to create services.

The services are classes with business logic, side-effects and state.

Getting Started

main.dart

void main() {
  Djinn().register(() => CounterService()); // singleton => same instance on every 'get' call
  // or
  Djinn().register(() => CounterService(), true); // scoped = true => new instance on every 'get' call
  Djinn().init();

  runApp(MyApp());
}

counter.dart

import 'package:djinn_flutter/djinn_flutter.dart';

class CounterState {
  int count;

  CounterState({this.count});
}

class CounterService extends DjinnService<CounterState> {
  var state = CounterState(count: 0);

  increment() {
    state.count++;
    updateState();
  }

  decrement() {
    state.count--;
    updateState();
  }
}

counter_widget.dart

class Counter extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _CounterState extends State<Counter> {
  final Counter counter = Djinn().get(); // <= Look this

  @override
  void initState() {
    super.initState();
    counter.listen(this); // <= Look this
  }

  @override
  void dispose() {
    counter.dispose(this); // <= Look this
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '${counter.state.count}', // <= Look this
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: counter.increment, // <= Look this
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

Listening for changes

The listen and dispose are functions to subscribe and unsubscribe for the service changes.

The updateState function called inside the services tell to DjinnService to propagate its state changes to the listeners.

Important

The init function is important, and must be called after all services was registered.

That function is responsible to create instances of the singleton services (scoped = false) and call it's init methods.

Communication between services

Just call the container.get() function inside the init function.

class ServiceA extends DjinnService {
  void printOk() {
    print('ok');
  }
}

class ServiceB extends DjinnService {
  ServiceA service;
  init() {
    service = Djinn().get();
  }
  
  doSomething() {
    service.printOk();
  }
}