Provider 4.1 sneek peak on context extension and watch, read and select methods.

main.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MultiProvider(
        providers: [
          ChangeNotifierProvider<Counter>(create: (_) => Counter()),
          Provider<Like>(
            create: (BuildContext context) => Like(context.read),
          )
        ],
        child: MyHomePage(title: 'Provider 4.1 Sneak Peek'),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  Widget build(BuildContext context) {
    final _counter = context.watch<Counter>();
    // final _increment = context.select((Counter counter) => counter.increment);
    final _add = context.select((Like value) => value.add);

    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have liked providers this many times:',
            ),
            Text(
              _counter.value.toString(),
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _add,
        tooltip: 'Increment',
        child: Icon(Icons.thumb_up),
      ),
    );
  }
}

class Counter extends ChangeNotifier {
  int _value = 0;

  int get value => _value;

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

class Like {
  Like(this._locator);
  final Locator _locator;

  void add() {
    _locator<Counter>().increment();
    _locator<Counter>().increment();
  }
}