i_spy 1.0.0

Visionary Software Solutions iSpy ==> OBSERVER, MEDIATOR, and Eventing Done Right.

example/i_spy_example.dart

import 'dart:math';

import 'package:i_spy/i_spy.dart';

final class Ping implements Event {}

final class Pong implements Event {}

final fate = Random();

final class Pinger implements Observable<Event>, Observer<Event> {
  Pinger() {
    SimpleEventingSystem.instance.add(this);
  }
  @override
  void notifyObservers(Event e) {
    SimpleEventingSystem.instance.notifyObservers(e);
  }

  void ping() => notifyObservers(Ping());

  @override
  void update(final Event e) {
    if (e is Pong) {
      if (fate.nextBool()) {
        ping();
      }
    }
  }
}

final class Scribe implements Observer<Event> {
  Scribe() {
    SimpleEventingSystem.instance.add(this);
  }
  @override
  void update(final Event e) {
    print(e.runtimeType);
  }
}

final class Ponger implements Observable<Event>, Observer<Event> {
  Ponger() {
    SimpleEventingSystem.instance.add(this);
  }
  @override
  void notifyObservers(final Event e) {
    SimpleEventingSystem.instance.notifyObservers(e);
  }

  @override
  void update(final Event e) {
    if (e is Ping) {
      if (fate.nextBool()) {
        pong();
      }
    }
  }

  void pong() => notifyObservers(Pong());
}

final class Finished implements Event {}

void main() {
  /// Basic demonstration of how OBSERVER and MEDIATOR enable decoupling between
  /// two components. [Pinger] and [Ponger] don't know about each other.
  final ping = Pinger();
  final pong = Ponger();
  final scribe = Scribe();

  /// nor do they know that there's a [Scribe] jotting down what happens.
  /// This loose coupling is a boon in many UI contexts.
  ping.ping();
  pong.pong();
  scribe.update(Finished());

  /// This example only showed a [SimpleEventingSystem] which allows all types
  /// of [Event]. Generic constrained versions of [Observer], [Observable], and
  /// [Mediator] are available for times when one doesn't mind having more
  /// instances around to ensure type safety. Check out the unit tests for more.
}