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rationalist [version] [ci]

Strongly influenced by substack's minimist nodejs module.


Add to your Gemfile:

gem 'rationalist'

For more info, see the original README below, with all JS replaced with Ruby.


parse argument options

This module is the guts of optimist's argument parser without all the fanciful decoration.


require 'rationalist'
argv = Rationalist.parse(ARGV)
p argv
$ ruby example/parse.rb -a beep -b boop
{:_=>[], :a=>"beep", :b=>"boop"}
$ ruby example/parse.js -x 3 -y 4 -n5 -abc --beep=boop foo bar baz
{ :_=>["foo", "bar", "baz"],
  :beep=>"boop" }


require 'rationalist'

argv = Rationalist.parse(args = ARGV, **opts, &unknown_block)

Return an argument object argv populated with the array arguments from args.

argv[:_] contains all the arguments that didn't have an option associated with them.

Numeric-looking arguments will be returned as numbers unless opts[:string] or opts[:boolean] is set for that argument name.

Any arguments after '--' will not be parsed and will end up in argv[:_].

options can be:

  • opts[:string] - a string or array of strings argument names to always treat as strings
  • opts[:boolean] - a boolean, string or array of strings to always treat as booleans. if true will treat all double hyphenated arguments without equal signs as boolean (e.g. affects --foo, not -f or --foo=bar)
  • opts[:alias] - an object mapping string names to strings or arrays of string argument names to use as aliases
  • opts[:default] - an object mapping string argument names to default values
  • opts[:stop_early] - when true, populate argv[:_] with everything after the first non-option
  • opts[:'--'] - when true, populate argv._ with everything before the -- and argv[:'--'] with everything after the --. Here's an example:
  • &unknown_block - a block which is invoked with a command line parameter not defined in the opts configuration object. If the function returns false, the unknown option is not added to argv.
>> Rationalist.parse('one two three -- four five --six'.split(' '), { '--': true })
{ :_=>["one", "two", "three"],
  :"--"=>["four", "five", "--six"] }

Note that with opts[:'--'] set, parsing for arguments still stops after the --.


With rubygems do:

gem install rationalist



rationalist was written by Jan Lelis and minimist was written by James Halliday.