stream_d 0.2.0

Stream that triggers the onDone event handler even when cancel() is called from a subscription. You can also add multiple onDone listeners and close all subscriptions from the stream. StreamD is based [...]

StreamD

Stream that triggers the onDone event handler even when cancel() is called from a subscription. You can also add multiple onDone listeners. StreamD is a wrapper on the default Dart Stream, but with an additional listenD method.

About StreamD

The minor hassle with default Dart Streams:

• the onDone event handler is not triggered when cancel() is called from a StreamSubscription, so it may be tricky to identify the exact moment when a StreamSubscription became no longer active if we don't have access to its StreamController on a specific layer of the App.

The solution when calling listenD

• onDone event handler is always triggered once the stream is no longer active, even when cancel() is called from a StreamSubscription.

StreamD also allows you to add a listener with addOnDone that won't replace the previous onDone callback and you can also close all StreamSubscription by calling closeAll

Comparison

final controller1 = StreamController();
final defaultStream = controller1.stream;
final defaultStreamSubscription = defaultStream.listen((event) {});
defaultStreamSubscription.onDone(() {
print("(2) Default Stream: onDone was triggered!");
});
print("(1) Default Stream: let's call cancel() on the subscription...");
defaultStreamSubscription.cancel();

final controller2 = StreamController();
final streamD = StreamD(controller2.stream);
final StreamSubscriptionD streamSubscriptionD = streamD.listenD((event) {});
streamSubscriptionD.addOnDone(() {
print("(2) With StreamD: onDone was triggered!");
});
print("(1) With StreamD: let's call cancel() on the subscription...");
streamSubscriptionD.cancel();

Output:

(1) Default Stream: let's call cancel() on the subscription...
(1) With StreamD: let's call cancel() on the subscription...
(2) With StreamD: onDone was triggered!

Getting started

dependencies:
  flutter:
    sdk: flutter
        
    # Add this line:
    stream_d: ^0.2.0

Initializing a StreamD

final streamD = StreamD(stream);

Usage

Listening

final StreamSubscriptionD subscription = streamD.listenD((event) {
    print(event);
});

Adding onDone listener to a subscription

final StreamSubscriptionD subscription = streamD.listenD((event) {});
subscription.addOnDone(() {
    print("onDone was called!");
});

Avoid calling listen and onDone from StreamD

It's important to call these methods when using StreamD and StreamSubscriptionD:

• call listenD, not listen
• call addOnDone, not onDone

listen and onDone are available for StreamBuilder internal usage only, so if you want to still use them, please use the default Dart Stream instead.

License

MIT

Contacting me

📧 [e-mail]