addObserver method

void addObserver(
  1. Object? observer, {
  2. String? key,
  3. NotificationCallback? callback,
})

Implementation

void addObserver(
  Object? observer, {
  String? key,
  NotificationCallback? callback,
}) {
  if (observer == null || key == null || callback == null) {
    log.severe('add: the param error');
    return;
  }
  _notifications.add(_Notification(key: key, observer: observer, callback: callback));
}