MVVM Design Pattern in Flutter

Question

we try to develop a flutter app and we create a stateful widget as a page .
we want to separate build function from other state variable and state function in 2 different fi

Answer 1

That's not the proper approach. You shouldn't split State and it's build method. The thing is, don't extend widgets. Compose them.

A correct way to achieve something similar is to use InheritedWidget. These will hold you data but do nothing else. And it's children will be able to request those datas using a MyInherited.of(context).

You could also create a builder. Something like :

typedef Widget MyStateBuilder(BuildContext context, MyStateState state);

class MyState extends StatefulWidget {
  final MyStateState builder;

  const MyState({this.builder}) : assert(builder != null);

  @override
  MyStateState createState() => new MyStateState();
}

class MyStateState extends State {
  String name;

  @override
  Widget build(BuildContext context) {
    return widget.builder(context, this);
  }
}