inline_l10n 0.1.0

Generate Flutter ARB localizations from inline, type-safe l10n markers.

inline_l10n

Generate Flutter ARB localization entries from English text kept next to the typed localization key that uses it.

Flutter's gen-l10n generates typed localization accessors from ARB files. inline_l10n reverses the authoring flow: write the English source text at its use site, generate app_en.arb, then let Flutter generate the accessors.

Text(l10n.settings.inline('Settings'))

At runtime, inline() returns the localized value from l10n.settings. Its English argument is used only by the generator.

What it does

• Extracts .inline(...) calls from Dart source with the Dart analyzer AST.
• Writes lib/resources/l10n/app_en.arb from the extracted English strings.
• Adds descriptions pointing to the defining source file.
• Keeps every non-English ARB file aligned with the generated English keys.
• Runs flutter gen-l10n after updating the ARB files.
• Fails when the same localization key has conflicting English source text.

This package is for Flutter apps that use the standard flutter gen-l10n workflow. It does not translate strings.

Install

Add the package to the Flutter app's pubspec.yaml:

dependencies:
  inline_l10n: ^0.1.0

Then run:

flutter pub get

The app must already have Flutter localization generation enabled:

# pubspec.yaml
flutter:
  generate: true

The generator requires this ARB layout:

arb-dir: lib/resources/l10n
template-arb-file: app_en.arb

For example, a compatible l10n.yaml can be:

arb-dir: lib/resources/l10n
template-arb-file: app_en.arb
output-localization-file: app_localizations.dart
output-class: AppLocalizations
nullable-getter: false

Usage

Import the runtime marker where localized text is used:

import 'package:inline_l10n/inline_l10n.dart';

Write the English source text alongside a generated AppLocalizations key:

final l10n = AppLocalizations.of(context);

Text(l10n.settings.inline('Settings'));

For arguments, use ICU placeholders in the English source and supply ARB placeholder metadata:

Text(
  l10n.greeting(name).inline(
    'Hello {name}',
    placeholders: {
      'name': {'type': 'String'},
    },
  ),
);

Run the generator from the Flutter app root:

dart run inline_l10n:gen_l10n

It creates or replaces app_en.arb, removes obsolete keys from every other app_*.arb file, and invokes flutter gen-l10n. Commit the generated ARB and Flutter localization output after reviewing the changes.

Recognized markers

The generator recognizes these forms:

l10n.key.inline('English text');
l10n.key(argument).inline('English {argument}');
AppLocalizations.of(context).key.inline('English text');

For local variables, the localization object must be named l10n. The source argument must be a string literal or adjacent string literals. String interpolation is not extracted; use ICU placeholders instead.

Important behavior

app_en.arb is the generated source of truth and is overwritten on each run. Other locale files retain only keys that still exist in app_en.arb; missing translations are not created. Keep ARB files under version control and review generator output before committing.

License

This project is licensed under the MIT License.