ever<T> function
Worker
ever<T>(
- RxInterface<
T> listener, - WorkerCallback<
T> callback, { - dynamic condition = true,
- Function? onError,
- void onDone()?,
- bool? cancelOnError,
Called every time listener
changes. As long as the condition
returns true.
Sample:
Every time increment() is called, ever() will process the condition
(can be a bool expression or a bool Function()
), and only call
the callback when condition
is true.
In our case, only when count is bigger to 5. In order to "dispose"
this Worker
that will run forever, we made a worker
variable. So, when the count value
reaches 10, the worker gets disposed, and releases any memory resources.
// imagine some counter widget...
class _CountController extends GetxController {
final count = 0.obs;
Worker worker;
void onInit() {
worker = ever(count, (value) {
print('counter changed to: $value');
if (value == 10) worker.dispose();
}, condition: () => count > 5);
}
void increment() => count + 1;
}
Implementation
Worker ever<T>(
RxInterface<T> listener,
WorkerCallback<T> callback, {
dynamic condition = true,
Function? onError,
void Function()? onDone,
bool? cancelOnError,
}) {
StreamSubscription sub = listener.listen(
(event) {
if (_conditional(condition)) callback(event);
},
onError: onError,
onDone: onDone,
cancelOnError: cancelOnError,
);
return Worker(sub.cancel, '[ever]');
}