Synopsis #

Observable provides a convenient mechanism of registering for events and dispatching notifications to listening clients.

How to use #

Inheriting from Observable #

The easiest way to use Observable is by inheriting from Observable, as given by:

import 'package:obvervable/obvervable.dart';

class Foo extends Observable

Clients register for notifications as illustrated in the following snippet:

Foo myFoo = new Foo();
myFoo.on.anEvent(() => print("AnEvent fired"));

Dispatching of events is done by invoking the dispatch method:

class Foo extends Observable
{
  .
  :
  .
  void method()
  {
    // carry out operations
    observer.dispatch("anEvent");
  }
}

Composition #

Since Dart does not support multiple inheritance, you may at times not be able to use the method outlined above. The alternative, then, is to use composition. Example:

import 'package:observable/observer.dart';
import 'package:observable/observer_events.dart';

class Foo extends SomeOtherClass
{
  Observer        observer;
  ObserverEvents  on;

  Foo()
    : observer = new Observer()
  {
    on = observer.on;
  }
}

Clients register for notifications and events are dispatched in the same manner as exemplified in the preceding section.