unscripted 0.3.3

Declarative command-line interface programming.

unscripted

Unscripted is a pub package for declarative command-line interface programming in dart. Command-line interfaces are defined using ordinary method and class declarations, minimally annotated with command-line metadata.
Reflection is used to derive the command-line interface from the declarations.
Command-line arguments are automatically injected into the method or class (constructor). This removes the need for boilerplate logic to define, parse, validate and assign variables for command-line arguments. Since the interface is defined in code, standard refactoring, testing, etc. tools can be used.

##Demo

cat.dart is a complete implementation of the *nix cat utility using unscripted.

##Usage

(For more detailed usage, see the API docs)

A simple script to output a greeting:

import 'package:unscripted/unscripted.dart';

main(arguments) => declare(greet).execute(arguments);

@Command(help: 'Outputs a greeting')
@ArgExample('--salutation Welcome --exclaim Bob', help: 'enthusiastic')
greet(
    @Rest(help: "Name(s) to greet")
    List<String> who, // A rest parameter, must be last positional.
    {String salutation : 'Hello', // An option, use `@Option(...)` for metadata.
     bool exclaim : false}) { // A flag, use `@Flag(...)` for metadata.

  print('$salutation ${who.join(' ')}${exclaim ? '!' : ''}');

}

(Compare to a traditiional version of this script.)

We can call this script as follows:

$ dart greet.dart Bob
Hello Bob
$ dart greet.dart --salutation Welcome --exclaim Bob
Welcome Bob!

###Automatic --help

Unscripted automatically defines and handles a --help/-h option, allowing for:

$ dart greet.dart --help
Outputs a greeting

Usage:

dart greet.dart [options] WHO...

Options:

-h, --help            Print this usage information.
    --salutation      (defaults to "Hello")
    --[no-]exclaim

Examples:

dart greet.dart --salutation Welcome --exclaim Bob # enthusiastic

###Sub-Commands

Sub-commands are also supported. In this case the script is defined as a class, whose instance methods can be annotated as sub-commands. Assume we have the following 'server.dart':

import 'package:unscripted/unscripted.dart';

main(arguments) => declare(Server).execute(arguments);

class Server {

  final String configPath;

  @Command(help: 'Manages a server')
  Server({this.configPath: 'config.xml'});

  @SubCommand(help: 'Start the server')
  start({bool clean}) {
    print('''
Starting the server.
Config path: $configPath''');
  }

  @SubCommand(help: 'Stop the server')
  stop() {
    print('Stopping the server.');
  }

}

We can call this script as follows:

$ dart server.dart start --config-path my-config.xml --clean
Starting the server.
Config path: my-config.xml

A 'help' sub-command is also added, which can be used as a synonym for '--help', which outputs all the basic help info plus a list of available commands:

$ dart server.dart help
Available commands:

  start
  help
  stop

Use "dart server.dart help [command]" for more information about a command.

and as indicated there, sub-command help is also available:

$ dart server.dart help stop
Stop the server

Usage:

dart server.dart stop [options]

Options:

-h, --help    Print this usage information.