Dart Async, Stream, StreamController, StreamTransformer

StreamController, StreamTransformer.fromHandlers

• dart:async library
• Stream class
  • map method
  • listen method
  • listen method
  • take method
  • where method
• StreamController class
• StreamTransformer<S, T> class
• Sink class

import 'dart:async';

class Cake {}
class Order {
  String type;
  Order(this.type);
}

void main() {
  final controller = new StreamController();

  final order = new Order('banana');
  final baker = new StreamTransformer.fromHandlers(handleData: (cakeType, sink){
    if( cakeType == 'chocolate') {
      sink.add(new Cake());
    } else {
      sink.addError('I cant bake that type!!!');
    }
  });

  controller.sink.add(order);
  controller.sink.add(new Order('apple'));
  controller.sink.add(new Order('chocolate'));

  controller.stream
    .map((order)=>order.type)
    .transform(baker)
    .listen(
      (cake) => print('Heres your cake $cake'),
      onError: (err) => print(err),
    );
}