functional_flutter
Tools for composing flutter widget trees in a functional manner.
Why
Your widget tree should be a function of your applications state, so why would you write widgets as classes and not functions?
functional_flutter encourages you to separate your state and properties from your widget definition. Rather than have a class that has properties and a build function implemented, you can lift the properties into a class and write FunctionalWidgets that take a properties class and return a widget.
Properties should always be a value type. I suggest you leverage built_value or meta's @immutable annotation for your prop classes.
If everything is a pure functional widget how can my widgets have state
The withState widget enhancer lets you lift state into a functional wrapper. For example:
@immutable
class AppProps {
final String title;
final int count;
final VoidCallback increment;
final VoidCallback decrement;
AppProps({this.title, this.count, this.increment, this.decrement});
}
FunctionalWidget<String> counterApp = withState(
0,
(String props, int state, SetState<int> setState) =>
new AppProps(
title: props,
count: state,
increment: () => setState((s) => s + 1),
decrement: () => setState((s) => s - 1),
),
)(_appContent);
Widget _appContent(AppProps props) => new MaterialApp(
title: props.title,
home: new Scaffold(
body: new Row(
children: <Widget>[
new RaisedButton(
onPressed: props.increment,
child: new Row(
children: <Widget>[
new Text('Increment'),
],
),
key: incrementButtonKey,
),
new RaisedButton(
onPressed: props.decrement,
child: new Row(
children: <Widget>[
new Text('Decrement'),
],
),
key: decrementButtonKey,
),
new Text(
'Count: ${props.count}',
key: counterKey,
),
],
),
),
);the withBuiltReduxStore enhancer also lets you subscribe to state from your built_redux store, if you are using built_redux as a state management solution.
