fetch method

@override Future<void> fetch(AsyncSource<T> source)

Replaces the current async source and subscribes to the new one.

This can be used to reload or switch the underlying async operation while keeping the same signal instance.

Example:

await signal.fetch(FutureSource(fetchData()));

Implementation

@override
Future<void> fetch(AsyncSource<T> source) async {
  if (isDisposed) return;
  final objId = Object();
  _objId = objId;

  _sourceDisposer?.call();
  _sourceDisposer = source.dispose;

  void emit(AsyncState<T> state) {
    if (_objId == objId) {
      value = state;
    }
  }

  try {
    await source.subscribe(emit);
  } finally {
    if (_objId == objId) {
      _objId = null;
      final disposer = _sourceDisposer;
      _sourceDisposer = null;
      disposer?.call();
    }
  }
}