once<T> function
Worker
once<T>(
- GetListenable<
T> listener, - WorkerCallback<
T> callback, { - dynamic condition = true,
- Function? onError,
- void onDone()?,
- bool? cancelOnError,
once()
will execute only 1 time when condition
is met and cancel
the subscription to the listener
stream right after that.
condition
defines when callback
is called, and
can be a bool or a bool Function()
.
Sample:
class _CountController extends GetxController {
final count = 0.obs;
Worker worker;
@override
Future<void> onInit() async {
worker = once(count, (value) {
print("counter reached $value before 3 seconds.");
}, condition: () => count() > 2);
3.delay(worker.dispose);
}
void increment() => count + 1;
}
Implementation
Worker once<T>(
GetListenable<T> listener,
WorkerCallback<T> callback, {
dynamic condition = true,
Function? onError,
void Function()? onDone,
bool? cancelOnError,
}) {
late Worker ref;
StreamSubscription? sub;
sub = listener.listen(
(event) {
if (!_conditional(condition)) return;
ref._disposed = true;
ref._log('called');
sub?.cancel();
callback(event);
},
onError: onError,
onDone: onDone,
cancelOnError: cancelOnError,
);
ref = Worker(sub.cancel, '[once]');
return ref;
}