i18n

https://pub.dev/packages/i18n
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i18n is a simple solution for Dart and Flutter that uses code generation to create efficient,...
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### Basic i18n Usage Example

Source: https://pub.dev/packages/i18n/versions/4.2.5/example

Demonstrates how to use the i18n package to display localized messages in English and German. It shows how to instantiate message classes and access translated strings, including pluralized forms.

```dart
// Copyright (c) 2018, 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:i18n/i18n.dart' as i18n;
import 'package:quick_log/quick_log.dart'; 

import 'messages.i18n.dart';
import 'messages_de.i18n.dart' as de;

void main() async {
  const log = Logger('Main', 'i18n');
  log.info('Hello from i18n!');
  log.info('Some english:');
  var m = Messages();
  print(m.generic.ok);
  print(m.generic.done);
  print(m.invoice.help);
  print(m.apples.count(1));
  print(m.apples.count(2));
  print(m.apples.count(5));

  log.info('Some German:');
  m = de.MessagesDe();
  print(m.generic.ok); // inherited from default
  print(m.generic.done);
  print(m.invoice.help);
  print(m.apples.count(1));
  print(m.apples.count(2));
  print(m.apples.count(5));

  // Override plurals for German or register support for your own language:
  i18n.registerResolver('de', (int count, i18n.QuantityType type) {
    if (type == i18n.QuantityType.cardinal && count == 1) {
      return i18n.QuantityCategory.one;
    }
    return i18n.QuantityCategory.other;
  });

  // See:
  // http://cldr.unicode.org/index/cldr-spec/plural-rules
  // https://www.unicode.org/cldr/charts/latest/supplemental/language_plural_rules.html
}

```

--------------------------------

### Add i18n Dependency to pubspec.yaml

Source: https://pub.dev/packages/i18n/install

This is an example of how the i18n dependency will appear in your pubspec.yaml file after running the add command.

```yaml
dependencies:
  i18n: ^4.2.6
```

--------------------------------

### Import i18n Package in Dart Code

Source: https://pub.dev/packages/i18n/versions/4.2.5/install

Import the i18n package into your Dart files to start using its functionalities.

```dart
import 'package:i18n/i18n.dart';
```

--------------------------------

### Using Generated Message Classes

Source: https://pub.dev/packages/i18n

Demonstrates how to import and use generated message classes for different locales. The choice of which message class to instantiate is up to the developer.

```dart
import 'messages.i18n.dart';
import 'messages_de.i18n.dart' as de;

void main() async {
  Messages m = Messages();
  print(m.apples.count(1));
  print(m.apples.count(2));
  print(m.apples.count(5));

  m = de.Messages_de(); // see? ExampleMessages_cs extends ExampleMessages
  print(m.apples.count(1));
  print(m.apples.count(2));
  print(m.apples.count(5));    
}
```

--------------------------------

### Running build_runner build

Source: https://pub.dev/packages/i18n

Command to perform a one-time build of message classes. Use this for production builds or when automatic rebuilding is not needed.

```bash
flutter packages pub run build_runner build
```

--------------------------------

### Flutter Integration with YAML

Source: https://pub.dev/packages/i18n

Shows how to create a YAML file for messages and import generated classes in a Flutter application. Requires `build_runner` and `i18n` dependencies.

```yaml
lib/messages/foo.i18n.yaml
```

```yaml
dependencies:
  flutter: 
    sdk: flutter
  i18n: any
  ...

dev_dependencies:
  build_runner: any
  flutter_test:
    sdk: flutter

```

```dart
import 'packages:my_app/messages/foo.i18n.dart'

... 

Foo m = Foo();
return Text(m.bar);
...
```

--------------------------------

### Pluralization Forms in Czech

Source: https://pub.dev/packages/i18n

Demonstrates how to define pluralization rules for languages that require more than two forms, using the `_plural` function with specific keys like `one`, `few`, and `many`.

```yaml
apples:
  _apples(int cnt): "${_plural(cnt, one:'jablko', few: 'jablka', many:'jablek')}"

```

--------------------------------

### Running build_runner watch

Source: https://pub.dev/packages/i18n

Command to run `build_runner` in watch mode for automatic rebuilding of message classes when YAML files change. Keep this command running during development.

```bash
flutter packages pub run build_runner watch
```

--------------------------------

### Define Messages in YAML

Source: https://pub.dev/packages/i18n

Define your application's translatable strings in a YAML file. This format supports simple key-value pairs and parameterized messages.

```yaml
lib/messages.i18n.yaml

button:
  save: Save
  load: Load
users:
  welcome(String name): "Hello $name!"
  logout: Logout

```

--------------------------------

### MIT License for i18n Package

Source: https://pub.dev/packages/i18n/versions/4.2.5/license

This snippet displays the full MIT license text. It grants broad permissions for use, modification, and distribution, with the condition that the copyright notice and disclaimer are included.

```plaintext
MIT License

Copyright (c) 2019 fnx.io

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

```

--------------------------------

### Add i18n to Flutter Project

Source: https://pub.dev/packages/i18n/versions/4.2.5/install

Use this command to add the i18n package as a dependency in your Flutter project.

```bash
$ flutter pub add i18n
```

--------------------------------

### Add i18n to Dart Project

Source: https://pub.dev/packages/i18n/versions/4.2.5/install

Use this command to add the i18n package as a dependency in your Dart project.

```bash
$ dart pub add i18n
```

--------------------------------

### YAML with Parameters and Pluralization

Source: https://pub.dev/packages/i18n

Define messages with parameters and pluralization rules directly in your YAML files. The `_plural` function is used to handle different grammatical forms based on a count.

```yaml
invoice:
  create: Create invoice
  delete: Delete invoice
  help: "Use this function
  to generate new invoices and stuff.
  Awesome!"
  count(int cnt): "You have created $cnt ${_plural(cnt, one:'invoice', many:'invoices')}."
apples:
  _apples(int cnt): "${_plural(cnt, one:'apple', many:'apples')}"
  count(int cnt): "You have eaten $cnt ${_apples(cnt)}."

```

--------------------------------

### Default Messages in YAML

Source: https://pub.dev/packages/i18n

Define your application's default messages in a YAML file. This serves as the primary source for your i18n strings.

```yaml
generic:
  ok: OK
  done: DONE
invoice:
  create: Create invoice
  delete: Delete invoice

```

--------------------------------

### Helper Functions for Pluralization

Source: https://pub.dev/packages/i18n

Utilize built-in helper functions like `_plural`, `_cardinal`, and `_ordinal` for handling grammatical variations of words based on quantity. `_plural` and `_cardinal` perform the same function.

```dart
String _plural(int count, {String zero, String one, String two, String few, String many, String other})

String _cardinal(int count, {String zero, String one, String two, String few, String many, String other})

String _ordinal(int count, {String zero, String one, String two, String few, String many, String other})

```

--------------------------------

### Accessing Localized Messages

Source: https://pub.dev/packages/i18n

Instantiate the generated `Messages` class and access localized strings using getter methods. Switch between languages by instantiating language-specific classes (e.g., `Messages_de`).

```dart
Messages m = Messages();
print(m.generic.ok); // output: OK
print(m.generic.done); // output: DONE

m = Messages_de();
print(m.generic.ok); // output: OK
print(m.generic.done); // output: ERLEDIGT

```

--------------------------------

### German Translations in YAML

Source: https://pub.dev/packages/i18n

Provide translations for different languages by creating separate YAML files, indicated by a language code suffix (e.g., `_de`).

```yaml
generic:
  ok: OK
  done: ERLEDIGT
invoice:
  create: Rechnung erstellen
  delete: Rechnung löschen

```

--------------------------------

### Use Generated Translations in Code

Source: https://pub.dev/packages/i18n

Instantiate the generated Messages class and use its methods to access translated strings. Supports parameterized messages.

```dart
Messages m = Messages();
print(m.users.welcome('World'));
// outputs: Hello World!

```

--------------------------------

### Generated Dart Classes for Messages

Source: https://pub.dev/packages/i18n

The code generation process creates Dart classes to represent your messages, providing type-safe access to localized strings and methods for parameterized messages.

```dart
class Messages {
    const Messages();
    InvoiceMessages get invoice => InvoiceExampleMessages(this);        
    ApplesMessages get apples => ApplesExampleMessages(this);
}
    
class InvoiceMessages {
    final Messages _parent;
    const InvoiceMessages(this._parent);
    String get create => "Create invoice";
    String get help => "Use this function to generate new invoices and stuff. Awesome!";
    String get delete => "Delete invoice";
    String count(int cnt) => "You have created $cnt ${_plural(cnt, one:'invoice', many:'invoices')}.";
}

class ApplesMessages {
    final Messages _parent;
    const ApplesMessages(this._parent);
    String _apples(int cnt) => "${_plural(cnt, one:'apple', many:'apples')}";
    String count(int cnt) => "You have eaten $cnt ${_apples(cnt)}.";
}         

```

--------------------------------

### Generated Dart Translation Classes

Source: https://pub.dev/packages/i18n

The i18n package generates Dart classes from your YAML message files. These classes provide type-safe access to your translations.

```dart
class Messages {
    const Messages();
    ButtonMessages get button => ButtonExampleMessages(this);
    UsersMessages get users => UsersExampleMessages(this);
}
class ButtonMessages {
    final Messages _parent;
    const ButtonMessages(this._parent);
    String get save => "Save";
    String get load => "Load";
}
class UsersMessages {
    final Messages _parent;
    const UsersMessages(this._parent);
    String get logout => "Logout";
    String welcome(String name) => "Hello $name!";
}

```
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