Dart Basic Part 4

stream_transformers.dart

import 'dart:async';

main(List<String> arguments) {

  var controller = StreamController<String>.broadcast();
  var streamTransformer = StreamTransformer<String, String>.fromHandlers(
      handleData: (String data, EventSink sink) {
        switch(data) {
          case "fool":
            sink.add("You $data");
            break;
          case "idiot":
            sink.add("You're $data");
            break;
          default:
            sink.add(data);
        }
      },
      handleError: (Object error, StackTrace stacktrace, EventSink sink) {
        sink.addError('Something went wrong: $error');
      },
      handleDone: (EventSink sink) {
        print("Controller Closed");
        sink.close();
      }
  );

  var streamController = controller.stream.transform(streamTransformer);

  streamController.listen(print);
  streamController.listen(print);



  controller.sink.add("fool");
  controller.sink.add("idiot");
  controller.sink.add("Howdy");
  controller.addError("Hello");
  controller.sink.close();
}