simple_streams 1.1.0

Simple Streams #

Normal broadcast streams can be a pain. You have to keep track of all stream subscriptions manually, or there can be memory leaks. simple_streams makes it easier by keeping track of those subscriptions for you. Let's look at the standard dart way of using a broadcast stream versus with simple_streams.


Standard Dart Method (Bad) #

First you must create a new broadcast StreamController and keep track of it's stream.

StreamController exampleStreamController = new StreamController.broadcast();
Stream exampleStream = exampleStreamController.stream;

Next, whenever you add a listener to the stream, you must manually keep track of the subscription.

exampleHandler(var e) {
  print('test');
}
StreamSubscription sub = exampleStream.listen(exampleHandler);

Finally, you must cancel the subscription when you are done with the stream. If you do not, you will get a memory leak.

sub.cancel();

Everytime you call .listen on that stream, it will create another StreamSubscription. You must keep track of all StreamSubscriptions and cancel all of them, otherwise you will create a memory leak. Or you can use simple streams to make it easier ;)

Simple Streams Method #

Instead of creating a stream controller (and probably a separate variable to hold its stream), just create a simple stream.

SimpleStream exampleStream = new SimpleStream();

Next, you can add listeners as many times as you want without keeping track of their subscriptions.

exampleHandler(var e) {
  print('test');
}
exampleStream.listen(exampleHandler);

Later, when you are done with the stream and it is going to be destroyed, call cancelAll() and it will cancel all of those subscriptions for you.

exampleStream.cancelAll();

SimpleStreamRouter #

With version 1.1.0 of simple streams, a new class was introduced, SimpleStreamRouter. SimpleStreamRouter is just a wrapper that can be used with any pre-existing stream. For example, you may use it with a DivElement's onClick stream. It will do the same thing as a SimpleStream and keep track of the StreamSubscriptions for you.

SimpleStreamRouter router = new SimpleStreamRouter(querySelector('#example-element').onClick);

Listen to the router without keeping track of StreamSubscriptions. You will receive the same Event by listening to the router as you would to the element's stream itself.

exampleHandler(MouseEvent e) {
  print("do something");
}
router.listen(exampleHandler);

When you are done with the router, you can call cancelAll() to avoid memory leaks.

router.cancelAll()

Source code: https://github.com/Nick-Anderssohn/simple-streams

See the example in the test folder.

How to install: https://pub.dartlang.org/packages/simple_streams

Version 1.1.0:

  • Added SimpleStreamRouter
  • Switched to MIT LICENSE

Version 1.0.3:

  • Bug fix

Version 1.0.2:

  • Bug fix

Version 1.0.1:

  • Changed library name from simple_stream to simple_streams

Version 1.0.0:

  • Initial release.

Use this package as a library

1. Depend on it

Add this to your package's pubspec.yaml file:


dependencies:
  simple_streams: ^1.1.0

2. Install it

You can install packages from the command line:

with pub:


$ pub get

Alternatively, your editor might support pub get. Check the docs for your editor to learn more.

3. Import it

Now in your Dart code, you can use:


import 'package:simple_streams/simple_streams.dart';
  
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The package version is not analyzed, because it does not support Dart 2. Until this is resolved, the package will receive a health and maintenance score of 0.

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The SDK constraint in pubspec.yaml doesn't allow the Dart 2.0.0 release. For information about upgrading it to be Dart 2 compatible, please see https://dart.dev/dart-2#migration.

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