Value Retriever

A package that creates a value controller that allows a value to be retrieved

Installation 💻

❗ In order to start using Value Retriever you must have the Dart SDK installed on your machine.

Add value_retriever to your pubspec.yaml:

dependencies:
  value_retriever:

Install it:

dart pub get

Usage and motivation ❔

Value Retreiver works on a similar way that Value Notifier in the way that it creates a controlled value, but unlike Valur Notifier, that allows users to listen for changes, Value Retreiver allows a value to be requested, which will be provided by any handlers that may be managing it.

An use case example. Imagine we are creating a Flutter app that edits text files, a simplified example would be:

class EditorScaffold extends StatefulWidget {
  State createState() => _EditorScaffoldState();
}

class _EditorScaffoldState extends State<EditorScaffold> {
  late final _textValue = ValueRetriever<String>();

  Future<void> _save() async {
    context.read<Repoisoty>().save(
      await _textValue.retrieve(),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: [
          Toolbar(
            icons: [
              SaveIcon(
                onPressed: _save,
              ),
            ],
          ),
          Expanded(child: EditorView(value: _textValue)),
        ],
      ),
    );
  }
}

class EditorView extends StatefulWidget {

  EditorView({ super.key, required this.value });

  final ValueRetriever<String> value;

  State createState() => _EditorViewState();
}

class _EditorViewState extends State<EditorView> {

  String value = '';

  @override
  void initState() {
    super.initState();

    widget.value.onRetrivement(_retrieveValue);
  }

  @override
  void dispose() {
    widget.value.removeHandler(_retrieveValue);

    super.dispose();
  }

  bool _retrieveValue(Completer<String> completer) {
    completer.complete(_value);
    return true;
  }

  @override
  Widget build(BuildContext context) {
    // omitted
  }
}