Samples for enhanced enums feature

enhanced_enums/.gitignore

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+# Files and directories created by pub.
+.dart_tool/
+.packages
+
+# Conventional directory for build output.
+build/

enhanced_enums/README.md

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+# Enhanced enums samples
+
+This a set of samples that demonstrates the enhanced enums syntax
+and shows some common use cases of the feature.
+
+This feature is part of Dart 2.17. The programs in this folder won't
+compile in earlier versions.
+
+## Instructions
+
+Read the source code in the `lib/` directory. The code is split into
+separate files according to topics or use cases. For instance,
+`lin/comparable_mixin.dart` demonstrates how a mixin can be used to add
+extra functionality to an enum.
+
+In `lib/complete_example.dart` you will find a complete example
+using all the functionality from enhanced enums.
+
+In `test/` you will find unit tests showing how the enums from the examples
+can be used. 

enhanced_enums/analysis_options.yaml

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+include: package:lints/recommended.yaml

enhanced_enums/lib/comparable.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Enum that implements a Comparable
+enum Ordering implements Comparable<Ordering> {
+  zero(0),
+  one(1),
+  many(99);
+
+  final int quantity;
+
+  const Ordering(this.quantity);
+
+  @override
+  int compareTo(Ordering other) => quantity - other.quantity;
+}

enhanced_enums/lib/comparable_mixin.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Enum that implements a Comparable using a mixin
+enum Ordering with EnumIndexOrdering<Ordering> {
+  zero,
+  few,
+  many;
+}
+
+/// Mixin that uses the enum index to create a comparable
+mixin EnumIndexOrdering<T extends Enum> on Enum implements Comparable<T> {
+  @override
+  int compareTo(T other) => index - other.index;
+}

enhanced_enums/lib/complete_example.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Complete example that showcases the different use cases for dart enums
+/// in a real scenario.
+///
+/// Enum that represents different types of vehicles.
+enum Vehicle with FlatTireMixin, Traveler implements Comparable<Vehicle> {
+  car(tires: 4, passengers: 5, carbonPerKilometer: 400),
+  bus(tires: 6, passengers: 50, carbonPerKilometer: 800),
+  bicycle(tires: 2, passengers: 1, carbonPerKilometer: 0);
+
+  const Vehicle({
+    required this.tires,
+    required this.passengers,
+    required this.carbonPerKilometer,
+  });
+
+  /// Number of tires of this Vehicle, part of [FlatTireMixin].
+  @override
+  final int tires;
+
+  /// Number of passengers the Vehicle can transport.
+  final int passengers;
+
+  /// Carbon in grams per kilometer.
+  final int carbonPerKilometer;
+
+  /// Method that calculates the Carbon Footprint of a Vehicle per passenger.
+  int get carbonFootprint => (carbonPerKilometer / passengers).round();
+
+  /// Comparable uses [carbonFootprint] to compare Vehicles.
+  @override
+  int compareTo(Vehicle other) => carbonFootprint - other.carbonFootprint;
+}
+
+/// Mixin that adds extra functionality.
+///
+/// This Mixin introduces the [tires] member and a method [costToReplaceTires]
+/// to calculate the cost of replacing the tires.
+mixin FlatTireMixin {
+  /// Fixed fee to add to the total cost.
+  static const fee = 50;
+
+  /// Number of tires getter, to be implemented by Enum.
+  int get tires;
+
+  /// Calculates the price to replace all tires.
+  int costToReplaceTires({required int pricePerTire}) {
+    return tires * pricePerTire + fee;
+  }
+}
+
+/// Mixin that adds Enum specific functionality
+///
+/// This mixin adds the [travel] method, that returns a String
+/// with the Enum name in it.
+///
+/// This mixin can access the property [name] from the Enum.
+mixin Traveler on Enum {
+  String travel() {
+    return 'I am traveling in a $name!';
+  }
+}

enhanced_enums/lib/members.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Enum with members and named constructor.
+///
+/// Also shows an example of [toString] override.
+enum LogPriority {
+  warning(2, "Warning"),
+  error(1, "Error"),
+  log.unknown("Log");
+
+  const LogPriority(this.priority, this.prefix);
+  const LogPriority.unknown(String prefix) : this(-1, prefix);
+
+  final int priority;
+  final String prefix;
+
+  @override
+  String toString() => '$prefix($priority)';
+}

enhanced_enums/lib/plain.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Plain enum.
+///
+/// This enum doesn't use any of enhancements.
+enum Plain { foo, bar, baz }

enhanced_enums/lib/typed_enum.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Enum with a generic type.
+///
+/// The type [T] is used to define the type of [List] the enum contains.
+enum EnumWithType<T> {
+  numbers<int>([1, 2, 3]),
+  strings<String>(['A', 'B', 'C']);
+
+  final List<T> items;
+
+  const EnumWithType(this.items);
+}

enhanced_enums/pubspec.yaml

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+name: enhanced_enums
+description: Samples that demonstrates the enhanced enums syntax
+
+# This example isn't intended for publishing on pub.dev.
+publish_to: none
+
+environment:
+  sdk: '>=2.17.0-182.1.beta <3.0.0'
+
+dev_dependencies:
+  lints: ^1.0.0
+  test: ^1.16.0

enhanced_enums/test/comparable_mixin_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/comparable_mixin.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Sort enum using compareTo in mixin', () {
+    // unsorted list
+    final list = [Ordering.many, Ordering.zero, Ordering.few];
+
+    // sort using compareTo
+    list.sort();
+
+    // list is sorted by amount
+    expect(list, [Ordering.zero, Ordering.few, Ordering.many]);
+  });
+}

enhanced_enums/test/comparable_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/comparable.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Sort Quantity enum using compareTo', () {
+    // unsorted list
+    final list = [Ordering.many, Ordering.zero, Ordering.one];
+
+    // sort using compareTo
+    list.sort();
+
+    // list is sorted by amount
+    expect(list, [Ordering.zero, Ordering.one, Ordering.many]);
+  });
+}

enhanced_enums/test/complete_example_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/complete_example.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Calculate efficiency of Vehicles', () {
+    expect(Vehicle.bicycle.carbonFootprint, 0);
+    expect(Vehicle.bus.carbonFootprint, 16);
+    expect(Vehicle.car.carbonFootprint, 80);
+  });
+
+  test('Sort Vehicles by carbon footprint', () {
+    final vehicles = Vehicle.values.toList();
+
+    // Sort using compareTo
+    vehicles.sort();
+
+    // Expect order from more efficient to less efficient
+    expect(vehicles, [Vehicle.bicycle, Vehicle.bus, Vehicle.car]);
+  });
+
+  test('Calculate cost to replace tires', () {
+    expect(Vehicle.bicycle.costToReplaceTires(pricePerTire: 10), 70);
+    expect(Vehicle.car.costToReplaceTires(pricePerTire: 60), 290);
+    expect(Vehicle.bus.costToReplaceTires(pricePerTire: 100), 650);
+  });
+
+  test('Travel in a car', () {
+    expect(Vehicle.car.travel(), 'I am traveling in a car!');
+  });
+}

enhanced_enums/test/members_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/members.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Enum with members to String', () {
+    expect(LogPriority.warning.toString(), 'Warning(2)');
+    expect(LogPriority.error.toString(), 'Error(1)');
+    expect(LogPriority.log.toString(), 'Log(-1)');
+  });
+}

enhanced_enums/test/plain_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/plain.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Plain enum names', () {
+    expect(Plain.foo.name, 'foo');
+    expect(Plain.bar.name, 'bar');
+    expect(Plain.baz.name, 'baz');
+  });
+
+  test('Plain enum index', () {
+    expect(Plain.foo.index, 0);
+    expect(Plain.bar.index, 1);
+    expect(Plain.baz.index, 2);
+  });
+
+  test('Get Plain enum values', () {
+    expect(Plain.values, [Plain.foo, Plain.bar, Plain.baz]);
+  });
+}

enhanced_enums/test/typed_enum_test.dart

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+// Copyright (c) 2022, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:enhanced_enums/typed_enum.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('Use typed enum', () {
+    expect(EnumWithType.numbers.items, [1, 2, 3]);
+    expect(EnumWithType.strings.items, ['A', 'B', 'C']);
+  });
+}