gem-hunter

Parse command line arguments directly into an annotation class using a standalone CLI or the Dart Build System.

Annotate a class with @CliOptions() from package:build_cli_annotations.

import 'package:build_cli_annotations/build_cli_annotations.dart';

part 'example.g.dart';

@CliOptions()
class Options {
  @CliOption(abbr: 'n', help: 'Required. The name to use in the greeting.')
  final String name;

  final bool nameWasParsed;

  late bool yell;

  @CliOption(defaultsTo: Language.en, abbr: 'l')
  late Language displayLanguage;

  @CliOption(negatable: false, help: 'Prints usage information.')
  late bool help;

  Options(this.name, {this.nameWasParsed = false});
}

enum Language { en, es }

Generate the .g.dart file with the standalone CLI (or Dart Build System) to create helpers that parse command line arguments and populate your class.

void main(List<String> args) {
  var options = parseOptions(args);
  if (!options.nameWasParsed) {
    throw ArgumentError('You must set `name`.');
  }
  print(options.name);
}

build_cli runs either as a standalone CLI or as a build_runner builder.

Add only build_cli_annotations to pubspec.yaml:

dependencies:
  build_cli_annotations: ^2.1.0

Run build_cli directly without adding build_runner to dev_dependencies:

$ dart run build_cli@
$ dart run build_cli@ --check

Pass --check (-c) in CI to verify that all generated .g.dart files match expected output without modifying disk. Pass optional file or directory paths (dart run build_cli@ bin/main.dart) to limit which files are scanned (defaults to lib, bin, example, test, and tool).

You can also enforce --check inside dart test without package:build_verify:

@Tags(['presubmit-only'])
@Timeout.factor(2)
library;

import 'dart:io';
import 'package:test/test.dart';

void main() {
  test('ensure build_cli output is up to date', () async {
    final result = await Process.run(
      Platform.resolvedExecutable,
      ['run', 'build_cli@2.3.1', '--check'],
    );
    expect(result.exitCode, 0, reason: '${result.stdout}\n${result.stderr}');
  });
}

If you combine multiple code generators in the same .g.dart file (such as package:json_serializable), add build_cli and build_runner to dev_dependencies:

dependencies:
  build_cli_annotations: ^2.1.0

dev_dependencies:
  build_cli: ^2.3.0
  build_runner: ^2.10.0

• build_cli_annotations contains the annotations you add to classes and members to tell build_cli what to do.
  • If the code you're annotating is in a published directory – lib, bin – put it in dependencies.
• build_cli contains the logic to generate the code.
• build_runner coordinates running multiple builders into shared .g.dart files.

Uses package:args under the covers.

• The package contains a fully documented end-to-end example.
• The test directory contains implementations that exercise most of the features of this package.
• Also look at the package:peanut source code. The options files in the src directory are the interesting files.