Yawpa

Yet Another Way to Parse Arguments is an argument-parsing library for Ruby.

Features

• POSIX or non-POSIX mode (supports subcommands using POSIX mode)
• Options can require an arbitrary number of parameters
• Options can be defined with a range specifying the allowed number of parameters

Example 1

require 'yawpa'

options = {
  version: {},
  verbose: {short: 'v'},
  get: {nargs: 1},
  set: {nargs: 2},
}
opts, args = Yawpa.parse(ARGV, options)
opts.each_pair do |opt, val|
end

Example 2

require 'yawpa'

options = {
  version: {},
  help: {short: 'h'},
}
opts, args = Yawpa.parse(ARGV, options, posix_order: true)
if opts[:version]
  puts "my app, version 1.2.3"
end
if args[0] == 'subcommand'
  subcommand_options = {
    'server': {nargs: (1..2), short: 's'},
    'dst': {nargs: 1, short: 'd'},
  }
  opts, args = Yawpa.parse(args, subcommand_options)
end

Using Yawpa.parse()

opts, args = Yawpa.parse(params, options, flags = {})

Parse input parameters looking for options according to rules given in flags

• params is the list of program parameters to parse.
• options is a hash containing the long option names as keys, and hashes containing special flags for the options as values (example below).
• flags is optional. It supports the following keys:
  • :posix_order: Stop processing parameters when a non-option is seen. Set this to true if you want to implement subcommands.

An ArgumentParsingException will be raised if an unknown option is observed or insufficient arguments are present for an option.

Example options

{
  version: {},
  verbose: {short: 'v'},
  server: {nargs: (1..2)},
  username: {nargs: 1},
  password: {nargs: 1},
}

The keys of the options hash can be either strings or symbols.

Options that have no special flags should have an empty hash as the value.

Possible option flags:

• :short: specify a short option letter to associate with the long option
• :nargs: specify an exact number or range of possible numbers of arguments to the option

Return values

The returned opts value will be a hash with the observed options as keys and any option arguments as values. The returned args will be an array of the unprocessed parameters (if :posix_order was passed in flags, this array might contain further options that were not processed after observing a non-option parameters.