multiple_result 4.0.0

Multiple results for dart. Inspired by dartz's Either and Kotlin's sealed classes

example/lib/main.dart

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          final result = _shouldIncrement(_counter);
          result.when(
            (success) {
              setState(() {
                _counter++;
              });
            },
            (error) {
              ScaffoldMessenger.of(context).showSnackBar(
                SnackBar(
                  content: Text(error.message),
                ),
              );
            },
          );
        },
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }

  Result<bool, IncrementException> _shouldIncrement(int currentCount) {
    if (currentCount + 1 == 10) {
      return Error(IncrementException("counter can't be bigger than 9"));
    } else {
      return Success(true);
    }
  }
}

class IncrementException implements Exception {
  final String message;

  IncrementException(this.message);
}