Flutter fix: Inherited widget example

typed_inherited.dart

// Fx for https://gist.github.com/stegrams/a2d17dc45bdae1ddfcc92cf6af96b80b/revisions#diff-a4501314e2bb2871a1a84da5ed71b87b
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      // Type: Foo<void> instead of Foo (=Foo<dynamic>)
      home: Foo<void>(child: Bar(), txt: "Happy 😁"),
    );
  }
}

class Foo<T> extends InheritedWidget {
  Foo({Key key, this.txt, this.child}) : super(key: key, child: child);
  
  final String txt;
  final Widget child;
  
  // Adding generic T
  static Foo of<T>(BuildContext context) =>
      context.dependOnInheritedWidgetOfExactType<Foo<T>>();
  @override
  bool updateShouldNotify(Foo old) => true;
}

class Bar extends StatelessWidget {
  @override
  // Requesting for Foo<void> instead of Foo(=Foo<dynamic>)
  Widget build(BuildContext ctx) => Text(Foo.of<void>(ctx)?.txt ?? "Sad 🤕");
}