Summary - Advanced streams

Combine broadcast, transformer and debounce to write an event processor.

Summary - Advanced streams

This group covered advanced stream topics: broadcast streams (many listeners), StreamTransformer (map/where/take), debounce and throttle, error handling and asyncExpand.

Core idea: transformers are lazy and chainable; data flows when a terminal (forEach/listen) is called. A broadcast stream allows many listeners.

Errors are caught via onError or try/catch; asyncExpand turns each element into a stream and concatenates them in order.

Exercise Summary: uppercase with map

Make main async. Add var s = Stream.fromIterable(['a', 'b']);. Add await s.map((x) => x.toUpperCase()).forEach(print);.

Show example solution

void main() async {
  var s = Stream.fromIterable(['a', 'b']);
  await s.map((x) => x.toUpperCase()).forEach(print);
}

Test yourself

Which one for many listeners?
- map
- asBroadcastStream
- take
- asyncExpand
Show answer

asBroadcastStream — asBroadcastStream allows many listeners.
Match the concepts

asBroadcastStream

Many listeners
.map

Transform
.take

First n
asyncExpand

Element → Stream

Error handling

var t = s.____((e) => print('error'));

Show answer

var t = s.handleError((e) => print('error'));

Next lesson: Reflection

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