unscripted 0.5.2+1

Declarative command-line interface programming.

unscripted

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

##Installation

pub global activate den
den install unscripted

##Usage

The following greet.dart script outputs a configurable greeting:

#!/usr/bin/env dart

import 'package:unscripted/unscripted.dart';

main(arguments) => declare(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')
greet(
    @Rest(help: 'Name(s) to greet.')
    List<String> who, {
      @Option(help: 'Alternate word to greet with e.g. "Hi".')
      String salutation : 'Hello',
      @Option(help: 'How many !\'s to append.')
      int enthusiasm : 0,
      @Flag(abbr: 'l', help: 'Put names on separate lines.')
      bool lineMode : false
    }) {

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

We can call this script as follows:

$ greet.dart Bob
Hello Bob
$ greet.dart --salutation Hi --enthusiasm 3 -l Alice Bob
Hi
  Alice,
  Bob!!!

##Automatic --help

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

$ greet.dart --help

Description:

  Print a configurable greeting

Usage:

  greet.dart [options] [WHO]...

Options:

      --salutation=<greeting>    Alternate <greeting> to greet with e.g. "Hi".
      --enthusiasm               How many !'s to append.
  -l, --line-mode                Put names on separate lines.
      --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.

Examples:

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

##Sub-Commands

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

class Server {

  final String configPath;

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

  @SubCommand(help: 'Start the server')
  start({bool clean: false}) {
    print('''
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:

  start
  help
  stop

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

$ server.dart help stop

Description:

  Stop the server

Usage:

  server.dart stop [options]

Options:

  -h, --help    Print this usage information.

##Parsers

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

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:

#!/usr/bin/env dart
// ...
@Command(plugins: const [const Completion()])

(Once pub supports cli's, the "shebang" line will no longer be required.)

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.

##Demo

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