Cake Factory

main.dart

import 'dart:async';

class Cake {

}

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


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

  final order = new Order('chocolate');

  // Create the factory to be used later.
  final baker = new StreamTransformer.fromHandlers(
      handleData: (cakeType, sink){
        // inspect the cakeType
        if (cakeType == 'chocolate'){
          sink.add(new Cake());
          /* Can add multiple orders
        sink.add(new Cake());
        sink.add(new Cake());
        */
        } else {
          sink.addError('I cant bake that type!!!');
        }
      }
  );

  // Pull off the data from the order
  controller.stream
  // Order Inspector
      .map((order) => order.type)
  // Give order to the Baker
      .transform(baker)
  // Pickup the output
      .listen(
          (cake) => print('Heres your cake $cake'),
      onError: (err) => print(err)
  );

  // Receive the order
  controller.sink.add(order);
  controller.close();
}