Really Cheap Command-Line Option Parsing in Ruby

Question

EDIT: Please, please, please read the two requirements listed at the bottom of this post before replying. People keep posting their new gems and li

Answer 1

https://github.com/soveran/clap

other_args = Clap.run ARGV,
  "-s" => lambda { |s| switch = s },
  "-o" => lambda { other = true }

46LOC (at 1.0.0), no dependency on external option parser. Gets the job done. Probably not as full featured as others, but it's 46LOC.

If you check the code you can pretty easily duplicate the underlying technique -- assign lambdas and use the arity to ensure the proper number of args follow the flag if you really don't want an external library.

Simple. Cheap.

---

EDIT: the underlying concept boiled down as I suppose you might copy/paste it into a script to make a reasonable command line parser. It's definitely not something I would commit to memory, but using the lambda arity as a cheap parser is a novel idea:

flag = false
option = nil
opts = {
  "--flag" => ->() { flag = true },
  "--option" => ->(v) { option = v }
}

argv = ARGV
args = []

while argv.any?
  item = argv.shift
  flag = opts[item]

  if flag
    raise ArgumentError if argv.size < arity
    flag.call(*argv.shift(arity))
  else
    args << item
  end
end

# ...do stuff...