Update event_bus.dart

[Vadaski]

Update EventBus constructor to allow custom EventBus.

[marcojakob]

Can you provide a small example of how you would use the EventBus like this?

[Vadaski]

sure,here is the example:https://github.com/OpenFlutter/Flutter-Notebook/tree/master/mecury_project/example/event_bus_demo

[marcojakob]

Thanks for the example. It's not very minimal but I get the picture.

What's the reason you are not using the BehaviorSubject directly in your example?

By adding an optional StreamController as parameter to the EventBus constructor the interface becomes a bit confusing. The sync parameter is ignored when a controller is specified.

I think by using special controllers, the behavior of EventBus can become hard to understand. I think it's better to use something like BehaviorSubject directly so that the special behavior is expected.

[Vadaski]

Thank you to remind me! I agree with the sync parameter will ignored when a controller is specified.I overlooked it.

This example shows two pages rely on CountEvent.They use StreamBuilder to listen for this event. If I use StreamController.broadcast I have to fire the Event after streamBuilder listen this stream.Otherwise I won't get the message.
BehaviorSubject can add last event to listener when they first listen.I don't need to care when listener listens.So I just fire the event before streamBuilder first listen.As you can see I fired the first CountEvent in the main function. EventBus become more powerful and easy to use.

I think using another constructor might be the better solution.

  EventBus({bool sync = false})
      : _streamController = StreamController.broadcast(sync: sync);

  EventBus.custom(StreamController controller) : _streamController = controller;

[marcojakob]

Thanks @Vadaski. I've made a small change and merged it. It's now as v1.1.0 on pub.

[Vadaski]

Great! I'm happy to make eventbus better. Thank you@marcojakob！