context_ref

A more convenient InheritedWidget alternative.

See context_plus for the ultimate convenience.

Features

• Ref<T> - a reference to a value of type T bound to a context or multiple contexts.
  • .bind(context, () => Value()) - create and bind value to a context. Automatically dispose() the value upon context disposal.
  • .bindLazy(context, () => Value()) - same as .bind(), but the value is created only when it's first accessed.
  • .bindValue(context, value) - bind an already created value to a context. The value is not disposed automatically.
  • .of(context) - get the value bound to the context or its nearest ancestor.

Getting started

flutter pub add context_ref

Wrap your app in a ContextRef.root widget.

ContextRef.root(
  child: MaterialApp(...),
);

(Optional) Wrap default error handlers with ContextRef.errorWidgetBuilder() and ContextRef.onError() to get better hot reload related error messages.

void main() {
  ErrorWidget.builder = ContextRef.errorWidgetBuilder(ErrorWidget.builder);
  FlutterError.onError = ContextRef.onError(FlutterError.onError);
}

Usage

Initialize and propagate a value down the widget tree:

final _state = Ref<_State>();

class Example extends StatelessWidget {
  const Example({super.key});

  @override
  Widget build(BuildContext context) {
    // No need to specify the `dispose` callback by hand if the _State is
    // disposable via the `dispose` method.
    // 
    // The `_State` will be created right await and disposed when the widget
    // is removed from the widget tree.
    //
    // Use `bindLazy` if you want to create the value only when it's first accessed.
    _state.bind(context, () => _State());
    return const _Child();
  }
}

class _Child extends StatelessWidget {
  const _Child();

  @override
  Widget build(BuildContext context) {
    final state = _state.of(context);
    ...
  }
}

Provide an already-initialized value down the tree:

final _params = Ref<Params>();

class Example extends StatelessWidget {
  const Example({
    super.key,
    required this.params,
  });
  
  final Params params;

  @override
  Widget build(BuildContext context) {
    // Whenever the `params` value change, the `_Child` widget will get rebuilt.
    // Values provided via `bindValue` are not disposed automatically.
    _params.bindValue(context, params);
    return const _Child();
  }
}

class _Child extends StatelessWidget {
  const _Child();

  @override
  Widget build(BuildContext context) {
    final params = _params.of(context);
    ...
  }
}

For more examples, see the example.

Libraries

context_ref