subscribe method

VoidCallback subscribe(void callback(T), { bool startNow = true, })

Subscribes to changes in the beacon returns a function that can be called to unsubscribe

If startNow is true, the callback will be called immediately with the current value of the beacon.

Implementation

VoidCallback subscribe(
  void Function(T) callback, {
  bool startNow = true,
}) {
  assert(!_isDisposed, 'Cannot subscribe to a disposed beacon.');

  if (_isDerived) {
    final sub = DerivedSubscription<T>(
      this as DerivedBeacon<T>,
      callback,
      startNow: startNow,
    );

    _observers.add(sub);

    return sub.dispose;
  }

  final sub = Subscription<T>(
    this,
    callback,
    startNow: startNow,
  );

  _observers.add(sub);

  return sub.dispose;
}