Yawpa

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

• 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

Yawpa can be used from another Ruby gem as a regular gem dependency, by adding a dependency on the "yawpa" gem at a particular version. For example:

  gem.add_dependency "yawpa", "~> 1.3"

Yawpa can also be used by simply copying the contents of the one source file into any project that desires to use it. This can be useful if you desire to avoid having any external dependencies, or if you are producing a redistributable standalone script.

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

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

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). Possible values:
  • nil: No special flags for this option (equivalent to {})
  • :boolean: The option is a toggleable boolean option (equivalent to {boolean: true})
  • Hash: 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
    • :boolean: if true, specify that the option is a toggleable boolean option and allow a prefix of "no" to turn it off.
    • :multi: if true, instead of the last value specified for this option being returned, an Array of all values specified for this option will be returned, allowing the argument to appear multiple times in the argument list
• 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.

{
  version: nil,
  verbose: {short: 'v'},
  server: {nargs: (1..2)},
  username: {nargs: 1},
  password: {nargs: 1},
  color: :boolean,
  scan: {nargs: 1, multi: true},
}

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

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
• :boolean: if true, specify that the option is a toggleable boolean option and allow a prefix of "no" to turn it off.
• :multi: if true, instead of the last value specified for this option being returned, an Array of all values specified for this option will be returned, allowing the argument to appear multiple times in the argument list

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).

• Add multi option flag to allow accepting multiple instances of an argument

• Remove use of Fixnum for Ruby 2.4+ compatibility

• Always return non-frozen strings

• Add :boolean option flag.
• Support nil or :boolean as shortcut option configuration values.
• Update documentation to YARD.
• Update specs to RSpec 3.

• Initial Release