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Dart 1 only

Declarative command-line interface programming.

unscripted pub package Build Status Coverage Status #

Define command-line interfaces using ordinary dart methods and classes.


pub global activate den
den install unscripted


The following greet.dart script outputs a configurable greeting:

#!/usr/bin/env dart

import 'package:unscripted/unscripted.dart';

main(arguments) => new Script(greet).execute(arguments);

// All metadata annotations are optional.
@Command(help: 'Print a configurable greeting', plugins: const [const Completion()])
@ArgExample('--salutation Hi --enthusiasm 3 Bob', help: 'enthusiastic')
    @Rest(help: 'Name(s) to greet.')
    List<String> who, {
      @Option(help: 'How many !\'s to append.')
      int enthusiasm : 0,
      @Flag(abbr: 'l', help: 'Put names on separate lines.')
      bool lineMode : false,
      @Option(name: 'greeting', help: 'Alternate word to greet with e.g. "Hi".')
      String salutation : 'Hello'
    }) {

  print(salutation +
        who.map((w) => (lineMode ? '\n  ' : ' ') + w).join(',') +
        '!' * enthusiasm);

We can call this script as follows:

$ greet.dart Bob
Hello Bob
$ greet.dart --enthusiasm 3 -l --greeting Hi Alice Bob

##Automatic --help

A --help/-h flag is automatically defined:

$ greet.dart --help


  Print a configurable greeting.


  greet.dart [options] [<who>...]

    <who>    Name(s) to greet.


      --completion         Tab completion for this command.

            [install]      Install completion script to .bashrc/.zshrc.
            [print]        Print completion script to stdout.
            [uninstall]    Uninstall completion script from .bashrc/.zshrc.

  -h, --help               Print this usage information.


      --enthusiasm         How many !'s to append.
                           (defaults to "0")

  -l, --line-mode          Put names on separate lines.
      --greeting           Alternate word to greet with e.g. "Hi".
                           (defaults to "Hello")


  greet.dart --greeting Hi --enthusiasm 3 Bob # enthusiastic


Sub-commands are represented as SubCommand-annotated instance methods of classes, as seen in the following server.dart:

#!/usr/bin/env dart

import 'dart:io';

import 'package:unscripted/unscripted.dart';
import 'package:path/path.dart' as path;

main(arguments) => new Script(Server).execute(arguments);

class Server {

  final String configPath;

      help: 'Manages a server',
      plugins: const [const Completion()])
  Server({this.configPath: 'config.xml'});

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

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


We can call this script as follows:

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

Help is also available for sub-commands:

$ server.dart help

Available commands:


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

$ server.dart help stop


  Stop the server


  server.dart stop [options]


  -h, --help    Print this usage information.


Any value-taking argument (option, positional, rest) can have a "parser" responsible for validating and transforming the string passed on the command line. You can give an argument a parser simply by giving it a type (such as int or DateTime) which has a static parse method, or by specifying the parser named argument of the argument's metadata (Option, Positional, or Rest).


Plugins allow you to mixin reusable chunks of cli-specific functionality (options/flags/commands) on top of your base interface.

To add a plugin to your script, just add an instance of the associated plugin class to the plugins named argument of your @Command annotation. The following plugins are available:

###Tab Completion

Add bash/zsh tab completion to your script:

@Command(/*...*/ plugins: const [const Completion()])

If your script already has sub-commands, this will add a completion sub-command (similar to npm completion), otherwise it adds a --completion option. These can then be used as follows:

# Try the tab-completion without permanently installing.
. <(greet.dart --completion print)
. <(server.dart completion print)

# Install the completion script to .bashrc/.zshrc depending on current shell.
# No-op if already installed.
greet.dart --completion install
server.dart completion install

# Uninstall a previously installed completion script.
# No-op if not installed.
greet.dart --completion uninstall
server.dart completion uninstall

Once installed, the user will be able to tab-complete all aspects of your cli, for example:

Option/Flag names: Say your script is a dart method with a longOptionName named parameter. This becomes --long-option-name in your cli, and once completion is installed, the user can type --l[TAB] and it will be completed to --long-option-name. It will also expand short options to their long equivalents, e.g. -vh[TAB] becomes --verbose --help.

Commands: If your script is a dart class having a @SubCommand() longCommandName method, that becomes a long-command-name sub-command in your cli, and the user can type l[TAB] and it will be completed to long-command-name.

Option/Positional/Rest values: The allowed named parameter of Option, Positional, and Rest specifies the allowed values, and thus completions, for those parameters. For example if you have @Option(allowed: const ['red', 'yellow', 'green']) textColor, and the user types --text-color g[TAB] this will become --text-color green. allowed can also be a callback of one of the following forms:

Iterable<String> complete(String text);
Iterable<String> complete();
Future<Iterable<String>> complete(String text);
Future<Iterable<String>> complete();

where if an arg (e.g. text here) is specified, it represents the last partial word typed by the user when completion is requested, which can be used to filter the results to match that prefix. If the arg is omitted, the filtering is done automatically for you. For example if the option/positional/rest represents a file name, you could emulate the builtin shell file name completion by returning a list of filenames in the current directory.

Tab completion is supported in cygwin, with one minor bug (#64).

###Other Plugins

There are several other plugins planned, and also the ability to write your own is planned, see #62.


den uses a large subset of the features above. Run pub global activate den to install, and then den -h to get a feel for the UX provided by unscripted.

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Declarative command-line interface programming.

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ansicolor, args, collection, mockable_filesystem, path, supports_color


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