docopt

a command line option parser that will make you smile

npm install docopt
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docopt – command line option parser, that will make you smile

docopt is a language for description of command-line interfaces. This is docopt implementation in CoffeeScript, that could be used for server-side CoffeeScript and JavaScript programs.

Isn't it awesome how modern command-line arguments parsers generate help message based on your code?!

Hell no! You know what's awesome? It's when the option parser is generated based on the help message that you write yourself! This way you don't need to write this stupid repeatable parser-code, and instead can write a beautiful help message (the way you want it!), which adds readability to your code.

Now you can write an awesome, readable, clean, DRY code like that:

doc = """
Usage:
  quick_example.coffee tcp <host> <port> [--timeout=<seconds>]
  quick_example.coffee serial <port> [--baud=9600] [--timeout=<seconds>]
  quick_example.coffee -h | --help | --version

"""
{docopt} = require '../docopt'

console.log docopt(doc, version: '0.1.1rc')

Hell yeah! The option parser is generated based on doc string above, that you pass to the docopt function.

API {docopt} = require 'docopt'

options = docopt(doc, {argv: process.argv[2..], help: true, version: null})

docopt takes 1 required and 3 optional keyword arguments:

  • doc should be a string with help message, written according to rules of docopt language. Here is a quick example of such a string:

      Usage: your_program [options]
    
      -h --help     Show this.
      -v --verbose  Print more text.
      --quiet       Print less text.
      -o FILE       Specify output file [default: ./test.txt].
    
  • argv is an optional argument vector; by default it is the argument vector passed to your program (process.argv[2..]). You can supply it with an array of strings (similar to process.argv) e.g. ['--verbose', '-o', 'hai.txt'].

  • help, by default true, specifies whether the parser should automatically print the help message (supplied as doc) in case -h or --help options are encountered. After showing the usage-message, the program will terminate. If you want to handle -h or --help options manually (as all other options), set help=false.

  • version, by default null, is an optional argument that specifies the version of your program. If supplied, then, if the parser encounters --version option, it will print the supplied version and terminate. version could be any printable object, but most likely a string, e.g. '2.1.0rc1'.

Note, when docopt is set to automatically handle -h, --help and --version options, you still need to mention them in the options description (doc) for your users to know about them.

The return value is an Object with properties (giving long options precedence), e.g:

{'--timeout': '10',
 '--baud': '4800',
 '--version': false,
 '--help': false,
 '-h': false,
 serial: true,
 tcp: false,
 '<host>': false,
 '<port>': '/dev/ttyr01'}
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