pushScope.dart

import 'package:flutter/material.dart';
import 'package:watch_it/watch_it.dart';

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

class Counter with ChangeNotifier {
  int _count = 0;

  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
    );
  }
}

class WatchItBuilder extends StatelessWidget with WatchItMixin {
  const WatchItBuilder({
    super.key,
    required this.builder,
  });

  final WidgetBuilder builder;

  @override
  Widget build(BuildContext context) => builder(context);
}

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

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Expanded(
          child: WatchItBuilder(
            builder: (context) {
              pushScope(init: (getIt) {
                getIt.registerSingleton<Counter>(Counter());
              });
              return const Page(
                title: 'Page 1',
              );
            },
          ),
        ),
        Expanded(
          child: WatchItBuilder(
            builder: (context) {
              pushScope(init: (getIt) {
                getIt.registerSingleton<Counter>(Counter());
              });
              return const Page(
                title: 'Page 2',
              );
            },
          ),
        ),
      ],
    );
  }
}

class Page extends StatelessWidget {
  final String title;

  const Page({super.key, required this.title});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: const Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have pushed the button this many times:'),
            Count(),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => di<Counter>().increment(),
        child: const Icon(Icons.add),
      ),
    );
  }
}

class Count extends StatelessWidget with WatchItMixin {
  const Count({super.key});

  @override
  Widget build(BuildContext context) {
    final counter = watchIt<Counter>();
    return Text(
      '${counter.count}',
      style: Theme.of(context).textTheme.headlineMedium,
    );
  }
}