Explanation on new parameters of listener in ref.listen?

[Ruzo]

Hi,

Is there an explanation somewhere about the nullable and non-nullable parameters in the new version of listener in ref.listen?

void listen<T>(
  ProviderListenable<T> provider,
  void Function(T?, T) listener, {
  void Function(Object, StackTrace)? onError,
})

Thanks!

[daniellampl]

The first parameter is the previous value and the second is the current value of the listened provider.

[Ruzo]

Ah, okay. Thanks a lot!

[ThomasKaputa]

Shouldn't the Documentation get updated?
There are examples with ref.listen with just one parameter which don't compile anymore. e.q.
final counterProvider = StateNotifierProvider<Counter, int>((ref) => Counter());

final anotherProvider = Provider((ref) {
ref.listen(counterProvider, (int count) {
print('The counter changed ${count}');
});
...
});

in https://riverpod.dev/docs/concepts/reading/