addEffect method

StreamSubscription<Snapshot<T>> addEffect(dynamic effect(Snapshot<T>))

Adds an effect function that gets called whenever the value changes.

Effects are a way to perform side effects when a reactive value changes without modifying the value itself. The effect function receives a Snapshot containing both the old and new values.

This method returns a StreamSubscription that can be used to cancel the effect if needed.

Example:

final counter = Reactive(0);

// Add a logging effect
counter.addEffect((snapshot) {
  print('Counter changed from ${snapshot.oldValue} to ${snapshot.newValue}');
});

// Add a persistence effect
counter.addEffect((snapshot) {
  saveToLocalStorage('counter', snapshot.newValue);
});

counter.value = 1; // Both effects will be triggered

Note: Effects are implemented using stream subscriptions. To avoid memory leaks, ensure you cancel any subscriptions when they're no longer needed, or dispose the reactive instance.

Implementation

StreamSubscription<Snapshot<T>> addEffect(Function(Snapshot<T>) effect) {
  return stream.listen((snapshot) {
    effect(snapshot);
  });
}