catalog_state_mutable.dart

class CatalogState {
  CatalogState({
    @required this.repository,
  });
  //
  final CatalogRepository repository;
  List<Item> items = [];

  Future<CatalogState> getItems() async {
    items = await repository.fetchItems();
    return this;
  }

  static Stream<void> deleteItem(
    CatalogState currentState,
    Item item,
  ) async* {
    final oldItems = [...currentState.items];
    try {
      currentState.items = oldItems.where((e) => e.id != item.id).toList();
      await currentState.repository.removeItem(item);
    } catch (e) {
      yield currentState.items = oldItems;
      rethrow;
    }
  }
}