osam 6.0.3

Lightweight and predictable state management

example/lib/main.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:osam/osam.dart';

void main() async {
  final core = Core();

  runApp(MaterialApp(
    home: App(core),
  ));
}

class App extends StatefulWidget {
  final Core core;

  const App(this.core);

  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  bool isVisible = true;
  var num = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: ValueListenableBuilder<List<News>>(
          valueListenable: widget.core.news,
          builder: (ctx, value, _) {
            return GestureDetector(
              child: Text(value.length.toString()),
              onTap: () {
                widget.core.news.update((value) => value.add(News(num)));
                num++;
              },
            );
          },
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          widget.core.news.update((value) {
            value.clear();
            value.add(News(0));
          });
        },
      ),
      body: ValueListenableBuilder<List<News>>(
        valueListenable: widget.core.news,
        builder: (ctx, value, _) {
          return ListView.builder(
            itemBuilder: (ctx, index) {
              return ValueListenableBuilder<bool>(
                valueListenable: value[index].isFavorite,
                key: ValueKey(value[index].id),
                builder: (ctx, isFavorite, _) => GestureDetector(
                  child: Container(
                    child: Row(
                      children: <Widget>[
                        Text(value[index].id.toString()),
                        Icon(isFavorite ? Icons.plus_one : Icons.minimize),
                      ],
                    ),
                    height: 200,
                    width: 200,
                    color: Colors.greenAccent,
                    margin: const EdgeInsets.all(8),
                  ),
                  onTap: () {
                    value[index].isFavorite.value = !isFavorite;
                  },
                ),
              );
            },
            itemCount: value.length,
          );
        },
      ),
    );
  }
}

class Core {
  var news = PropertyNotifier(<News>[]);
}

class News {
  var isFavorite = PropertyNotifier(false);
  final int id;

  News(this.id);
}