events.dart

/* pseudo-ish code
The code can be somewhat simplified by showing the dialog directly in onPressed().
But since the dialog can't be dismissed w/o a BuildContext, I'd still have to listen for a state,
so it's cleaner to treat both show/dismiss the same way, i.e. by listening to DataBloc's state change.

The problem with all of this, as you can see, is that the many of the events and states serve no other
purpose than to display the dialog. Specifically, ItemTransmogrifyStartedEvent/State, ItemTransmogrifyDoneEvent/State.

My question here: how would you go about this?
*/


// this handles all items + extra surrounding data
DataBloc {
  mapEventToState(event) {
    if (event is DataTransmogrifyRequestEvent) {
      _transmogrify(event.data)
    }
  }
  _transmogrify(data) {
    yield DataTransmogrifyStartedState();
    // perform transmogrification with parameter 'data'
    yield DataTransmogrifyDoneState();
  }
}

// this handles the ItemsWidget
ItemsBloc {
  List<Item> items;

  ctor() {
     dataBloc.listen((state) {
       if (state == DataTransmogrifyStartedState) {
         dispatch(ItemTransmogrifyStartedEvent);
       }
     })

  mapEventToState(event) {
    if (event is ItemButtonPressedEvent) {
      dataBloc.dispatch(DataTransmogrifyRequestEvent);
     }
     if (event is ItemTransmogrifyStartedEvent) {
       dispatch(ItemTransmogrifyStartedState);
     }
     if (event is ItemTransmogrifyDoneEvent) {
       dispatch(ItemTransmogrifyDoneState);
     }
  }
}

ItemsWidget {
 build() {
  return BlocListener<ItemBloc, ItemState>(
    listener: (context, state) {
      if (state is ItemTransmogrifyStartedState) {
        showDialog(...)
      }
      if (state is ItemTransmogrifyDoneState) {
        Navigator....pop();
      }
    },
    build: (context, state) {
      return Button(
        onPressed: () => itemsBloc.dispatch(ItemButtonPressedEvent)
      );
    }
  );
 }
}