arguable

Usage-first argument parser.

Usage first argument parser for Node.js.

Arguable is a command line parser that lends structure to your command line programs. You can use Arguable as a simple command line parser, or you can use it to organize your program in a master program with any number of sub-commands in the style of git, apt-get or yum.

Arguable starts with your usage message. It extracts the program arguments from the usage message. Arguable compels you to write a usage message in order to get your command line to parse.

#!/usr/bin/env node
 
/*
 
  ___ usage ___ en_US ___
  usage: frobinate [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -p, --processes   [count]   number of processes to run in parallel
 
  description:
 
  frobinate will reticuatle the splines in all of your transmogrifier
  files, optionally in parallel. The `--processes` option is the number
  of processes to run concurrently, defaulting to one.
 
  ___ . ___
 
*/
 
var frobinate = require('../lib/frobinator').frobinate
 
require('arguable')(module, function (programcallback) {
    program.helpIf(program.param.help)
    frobinate(program.param.processes, .param.argv, callback)
})

In the spirit of opinionated software Arguable starts with a full help message, because I believe that a full usage message is important for a command line program.

Usage messages are important to Node.js; Linux users have become accustomed to having a lot of context at their disposal when they invoke --help. Windows users are without a decent manual page system, so they tend to rely on usage messages to discover what their software can do.

I don't want my command line library to assemble a usage message from a method chained, declarative API. The usage message and arguments of a command line program are the user interface. I do not expect its implementation to be trivial. I do not want to delegate the details to a module.

It would rather have spend time composing a nicely formatted usage message, with the ability to see the whole message, then work from that message.

Your usage message must contain a long option for every option; short options are optional.

If you have a synonym for one of your commands, simply declare it separately and document it separately.

The only argument validation that Arguable* performs is to check that arguments that accept a parameter have a parameter; that arguments that don't accept a parameter don't have a parameter. Type checking is meant to be performed by the program itself.

#!/usr/bin/env node
 
/*
 
  ___ usage ___ en_US ___
  usage: frobinate [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -p, --processes   [count]   number of processes to run in parallel
  -t, --threads     [count]   same as `--proceses`
  -v, --verbose               toggle verbose output
 
  description:
 
  frobinate will reticuatle the splines in all of your transmogrifier
  files, optionally in parallel. The `--processes` option is the number
  of processes to run concurrently, defaulting to one.
 
  ___ . ___
 
*/
 
require('arguable')(module, function (programcallback) {
  program.helpIf(program.param.help)
  var processes = options.processes || options.threads || 1
  frobinate(processes, program.param.verbose, program.argv, callback)
});

Ed: Add an example of type checking — integer — to the example above.

Ed: The error checking example would also show how to report errors.

Arguable allows you to specify sub-commands in the style of git, apt-get or yum. Add the sub-command name to your usage description. Arguable will select the correct help message based on the program arguments.

/*
 
  ___ run, usage ___ en_US ___
  usage: frobinate run [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -p, --processes     [count] number of processes to run in parallel
 
  description:
 
  frobinate will reticuatle the splines in all of your transmogrifier
  files, optional in parallel. The `--processes` option is the number of
  processes to run concurrently, defaulting to zero.
 
  ___ compile, usage ___ en_US ___
  usage: frobinate compile [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -s, --strict                strict interpretation of the ISO 33465
                              Frobination Standard.
  -p, --prefix                prefix for frobination identifiers
 
  description:
 
  `frobinate compile` will accelerate frobination by compling it to
  intermediate output interpreted code (IOIC) then frobinating the hell
  out it.
 
  ___ . ___
 
*/
 
var arguable = require('arguable')
  , frobinator = require('../lib/frobinator')
  , icoc
  ;
 
require('arguable')(module, function (programcallback) {
    program.helpIf(program.param.help)
    switch (program.command) {
    case 'compile':
        ioic = frobinator.prepare(program.param.strict, program.param.prefix, program.argv)
        frobinator.frobinator(ioic, callback)
        break
    case 'run':
        frobinator.frobinate(program.param.processes, program.argv, callback)
        break
    default:
        program.abend('unknown command')
  }
})

Arguable supports internationalization. Simply write additional usage messages in other languages following the default language, marking the additional languages with their locale string. You can then invoke the parser passing the current locale string as the first argument.

 
/*
 
___ usage ___ en_US ___
usage: awaken
 
  Good morning!
___ usage ___ fi_FI ___
käyttö: awaken
 
  Hyvää huomenta!
___ . ___
 
*/
 
require('arguable')(module, function (programcallback) {
    console.log(program.usage)
    callback()
})

We can run the above program with our LANG environment variable set to one of the supported languages.

$ LANG=fi_FI.UTF-8 node awaken.js
käyttö: awaken
 
  Hyvää huomenta!

The above will print the Finnish version of the help message. You can pass the language specified in the users LANG environment variable directly to parse. If no such language translation exists, it falls back to the first translation encountered.

Note that command names and switches are not internationalized. Changing the user's language preferences is not supposed change the program interface.

You can define internationalized error messages. Add a strings section to following your usage defintion

#!/usr/bin/env node
 
/*
 
  ___ usage: en_US ___
  usage: frobinate [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -p, --processes   [count]   number of processes to run in parallel
 
  description:
 
  frobinate will reticuatle the splines in all of your transmogrifier
  files, optionally in parallel. The `--processes` option is the number
  of processes to run concurrently, defaulting to one. Note that you
  cannot run more than four processes at time.
 
  ___ strings ___
 
    too many processes:
      You choose %d processes to frobinate %s, but the maximum is 4.
 
  ___ usage ___
 
*/
 
require('arguable')(__filename, function (options) {
  if (options.help) throw new Error("usage");
  if (options.processes > 4) {
    options.abend('too many processes', options.processes, options.argv[0]);
  }
  require('../lib/frobinator').frobinate(options.processes, options.argv);
});

Arguments are fed to util.format and the result is printed in your language message to standard out.

Each language can have it's own message section. Your translation might need to reorder the arguments to fit a different sentence structure. Here's an example of reordering, however we're still in English, because it's really all I know.

Oh, I'd love a patch if you have an example in your language, and your language is not English.

#!/usr/bin/node
 
/*
 
  ___ usage ___ en_US ___
  usage: frobinate [options] [file...] [file]
 
  options:
 
  -h, --help                  display this message
  -p, --processes   [count]   number of processes to run in parallel
 
  description:
 
  frobinate will reticuatle the splines in all of your transmogrifier
  files, optionally in parallel. The `--processes` option is the number
  of processes to run concurrently, defaulting to one. Note that you
  cannot run more than four processes at time.
 
  ___ $ ___
 
    too many processes (2, 1):
      You choose frobinate %s using %d processes, but the maximum is 4.
 
  ___ . ___
 
*/
 
require('arguable')(module, function (programcallback) {
    program.helpIf(program.param.help)
    if (program.param..processes > 4) {
        program.abend('too many processes', program.param.processes, options.argv[0])
    }
    require('../lib/frobinator').frobinate(program.param.processes, program.argv, callback)
})

todo: Move this into GitHub Releases!

Changes for each release.

  • Upgrade Proof to 0.0.32. #54.

Sun Jun 30 14:57:25 UTC 2013

  • Implement options.fatal. #52.
  • Upgrade to Proof 0.0.30. #51. #50.
  • Use parseFloat to parse numeric. #41.
  • Fix variable leaked into global namespace. #49.
  • Provide format to abended function. #35.
  • Make string resources generally available. #43.
  • Tidy, delete dead code. #43. #35.
  • Add coverage chicklet to README.md.
  • Remove bc install from Travis CI build.
  • Remove .npmignore. #47.

Thu Mar 21 05:26:43 UTC 2013

  • Use a usage message for parse errors. #44.
  • Pass Error to user provided abnormal exit callback. #45.
  • Make no matching usage a plain old exception. #46.
  • Begin a design diary.
  • Add an MIT LICENSE and a contribution guide.
  • Rename errors function to strings. #42.
  • Reorder and format error messages. #29.
  • Drop support for Node.js 0.6.
  • Fix and test Options.help. #38.
  • Use Options.abend in arguments parser. #36.
  • Complete internal conversion to an Options class.
  • Extract globs into an expandable project. #37.

Thu Feb 28 07:23:51 UTC 2013

  • Remove defaultLanguage from params. #33.
  • Error when usage message is missing. #28.

Thu Feb 21 07:42:25 UTC 2013

  • Fix formatting of change log in README.md. #31.
  • Create Options class. #32.
  • Implement sub-commands in usage markup. #30.
  • Add .js suffix to tests. #26.
  • Use markup for usage messages instead of guessing locale based on language. #27.
  • Wrap main body of program in a try/catch block. #25.

Tue Jul 10 19:02:23 UTC 2012

  • Update README.md help messages with short options first, proper terminator. #19.
  • Flatten arguments passed to parse. #18.
  • Internationalization. #8.
  • Add $given, a list of given parameters. #16.
  • Remove sort from flatten. #17.

Tue Jul 10 05:32:25 UTC 2012

  • Implement flatten. #15.
  • Use :usage to end usage message. #13.
  • Short opts before long opts in usage message list of options. #14.

Mon Jul 9 18:24:28 UTC 2012

  • Implement argument parsing. #4.

Mon Jul 9 00:19:49 UTC 2012

  • Give matched file relative to base. #11.

Sun Jul 8 23:29:58 UTC 2012

  • Created change log. #10.
  • Build on Travis CI. #9.
  • Bash wildcards on Windows. #7. #6. #5.

Sun Jul 8 02:53:58 UTC 2012