class OptionParser

OptionParser ↑

New to OptionParser? ↑

See the Tutorial.

Introduction ↑

OptionParser is a class for command-line option analysis. It is much more advanced, yet also easier to use, than GetoptLong, and is a more Ruby-oriented solution.

Features ↑

  1. The argument specification and the code to handle it are written in the same place.

  2. It can output an option summary; you don’t need to maintain this string separately.

  3. Optional and mandatory arguments are specified very gracefully.

  4. Arguments can be automatically converted to a specified class.

  5. Arguments can be restricted to a certain set.

All of these features are demonstrated in the examples below. See make_switch for full documentation.

Minimal example ↑

require 'optparse'

options = {}
OptionParser.new do |parser|
  parser.banner = "Usage: example.rb [options]"

  parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
    options[:verbose] = v
  end
end.parse!

p options
p ARGV

Generating Help ↑

OptionParser can be used to automatically generate help for the commands you write:

require 'optparse'

Options = Struct.new(:name)

class Parser
  def self.parse(options)
    args = Options.new("world")

    opt_parser = OptionParser.new do |parser|
      parser.banner = "Usage: example.rb [options]"

      parser.on("-nNAME", "--name=NAME", "Name to say hello to") do |n|
        args.name = n
      end

      parser.on("-h", "--help", "Prints this help") do
        puts parser
        exit
      end
    end

    opt_parser.parse!(options)
    return args
  end
end
options = Parser.parse %w[--help]

#=>
   # Usage: example.rb [options]
   #     -n, --name=NAME                  Name to say hello to
   #     -h, --help                       Prints this help

Required Arguments ↑

For options that require an argument, option specification strings may include an option name in all caps. If an option is used without the required argument, an exception will be raised.

require 'optparse'

options = {}
OptionParser.new do |parser|
  parser.on("-r", "--require LIBRARY",
            "Require the LIBRARY before executing your script") do |lib|
    puts "You required #{lib}!"
  end
end.parse!

Used:

$ ruby optparse-test.rb -r
optparse-test.rb:9:in `<main>': missing argument: -r (OptionParser::MissingArgument)
$ ruby optparse-test.rb -r my-library
You required my-library!

Type Coercion ↑

OptionParser supports the ability to coerce command line arguments into objects for us.

OptionParser comes with a few ready-to-use kinds of type coercion. They are:

We can also add our own coercions, which we will cover below.

Using Built-in Conversions ↑

As an example, the built-in Time conversion is used. The other built-in conversions behave in the same way. OptionParser will attempt to parse the argument as a Time. If it succeeds, that time will be passed to the handler block. Otherwise, an exception will be raised.

require 'optparse'
require 'optparse/time'
OptionParser.new do |parser|
  parser.on("-t", "--time [TIME]", Time, "Begin execution at given time") do |time|
    p time
  end
end.parse!

Used:

$ ruby optparse-test.rb  -t nonsense
... invalid argument: -t nonsense (OptionParser::InvalidArgument)
$ ruby optparse-test.rb  -t 10-11-12
2010-11-12 00:00:00 -0500
$ ruby optparse-test.rb  -t 9:30
2014-08-13 09:30:00 -0400

Creating Custom Conversions ↑

The accept method on OptionParser may be used to create converters. It specifies which conversion block to call whenever a class is specified. The example below uses it to fetch a User object before the on handler receives it.

require 'optparse'

User = Struct.new(:id, :name)

def find_user id
  not_found = ->{ raise "No User Found for id #{id}" }
  [ User.new(1, "Sam"),
    User.new(2, "Gandalf") ].find(not_found) do |u|
    u.id == id
  end
end

op = OptionParser.new
op.accept(User) do |user_id|
  find_user user_id.to_i
end

op.on("--user ID", User) do |user|
  puts user
end

op.parse!

Used:

$ ruby optparse-test.rb --user 1
#<struct User id=1, name="Sam">
$ ruby optparse-test.rb --user 2
#<struct User id=2, name="Gandalf">
$ ruby optparse-test.rb --user 3
optparse-test.rb:15:in `block in find_user': No User Found for id 3 (RuntimeError)

Store options to a Hash ↑

The into option of order, parse and so on methods stores command line options into a Hash.

require 'optparse'

options = {}
OptionParser.new do |parser|
  parser.on('-a')
  parser.on('-b NUM', Integer)
  parser.on('-v', '--verbose')
end.parse!(into: options)

p options

Used:

$ ruby optparse-test.rb -a
{:a=>true}
$ ruby optparse-test.rb -a -v
{:a=>true, :verbose=>true}
$ ruby optparse-test.rb -a -b 100
{:a=>true, :b=>100}

Complete example ↑

The following example is a complete Ruby program. You can run it and see the effect of specifying various options. This is probably the best way to learn the features of optparse.

require 'optparse'
require 'optparse/time'
require 'ostruct'
require 'pp'

class OptparseExample
  Version = '1.0.0'

  CODES = %w[iso-2022-jp shift_jis euc-jp utf8 binary]
  CODE_ALIASES = { "jis" => "iso-2022-jp", "sjis" => "shift_jis" }

  class ScriptOptions
    attr_accessor :library, :inplace, :encoding, :transfer_type,
                  :verbose, :extension, :delay, :time, :record_separator,
                  :list

    def initialize
      self.library = []
      self.inplace = false
      self.encoding = "utf8"
      self.transfer_type = :auto
      self.verbose = false
    end

    def define_options(parser)
      parser.banner = "Usage: example.rb [options]"
      parser.separator ""
      parser.separator "Specific options:"

      # add additional options
      perform_inplace_option(parser)
      delay_execution_option(parser)
      execute_at_time_option(parser)
      specify_record_separator_option(parser)
      list_example_option(parser)
      specify_encoding_option(parser)
      optional_option_argument_with_keyword_completion_option(parser)
      boolean_verbose_option(parser)

      parser.separator ""
      parser.separator "Common options:"
      # No argument, shows at tail.  This will print an options summary.
      # Try it and see!
      parser.on_tail("-h", "--help", "Show this message") do
        puts parser
        exit
      end
      # Another typical switch to print the version.
      parser.on_tail("--version", "Show version") do
        puts Version
        exit
      end
    end

    def perform_inplace_option(parser)
      # Specifies an optional option argument
      parser.on("-i", "--inplace [EXTENSION]",
                "Edit ARGV files in place",
                "(make backup if EXTENSION supplied)") do |ext|
        self.inplace = true
        self.extension = ext || ''
        self.extension.sub!(/\A\.?(?=.)/, ".")  # Ensure extension begins with dot.
      end
    end

    def delay_execution_option(parser)
      # Cast 'delay' argument to a Float.
      parser.on("--delay N", Float, "Delay N seconds before executing") do |n|
        self.delay = n
      end
    end

    def execute_at_time_option(parser)
      # Cast 'time' argument to a Time object.
      parser.on("-t", "--time [TIME]", Time, "Begin execution at given time") do |time|
        self.time = time
      end
    end

    def specify_record_separator_option(parser)
      # Cast to octal integer.
      parser.on("-F", "--irs [OCTAL]", OptionParser::OctalInteger,
                "Specify record separator (default \\0)") do |rs|
        self.record_separator = rs
      end
    end

    def list_example_option(parser)
      # List of arguments.
      parser.on("--list x,y,z", Array, "Example 'list' of arguments") do |list|
        self.list = list
      end
    end

    def specify_encoding_option(parser)
      # Keyword completion.  We are specifying a specific set of arguments (CODES
      # and CODE_ALIASES - notice the latter is a Hash), and the user may provide
      # the shortest unambiguous text.
      code_list = (CODE_ALIASES.keys + CODES).join(', ')
      parser.on("--code CODE", CODES, CODE_ALIASES, "Select encoding",
                "(#{code_list})") do |encoding|
        self.encoding = encoding
      end
    end

    def optional_option_argument_with_keyword_completion_option(parser)
      # Optional '--type' option argument with keyword completion.
      parser.on("--type [TYPE]", [:text, :binary, :auto],
                "Select transfer type (text, binary, auto)") do |t|
        self.transfer_type = t
      end
    end

    def boolean_verbose_option(parser)
      # Boolean switch.
      parser.on("-v", "--[no-]verbose", "Run verbosely") do |v|
        self.verbose = v
      end
    end
  end

  #
  # Return a structure describing the options.
  #
  def parse(args)
    # The options specified on the command line will be collected in
    # *options*.

    @options = ScriptOptions.new
    @args = OptionParser.new do |parser|
      @options.define_options(parser)
      parser.parse!(args)
    end
    @options
  end

  attr_reader :parser, :options
end  # class OptparseExample

example = OptparseExample.new
options = example.parse(ARGV)
pp options # example.options
pp ARGV

Shell Completion ↑

For modern shells (e.g. bash, zsh, etc.), you can use shell completion for command line options.

Further documentation ↑

The above examples, along with the accompanying Tutorial, should be enough to learn how to use this class. If you have any questions, file a ticket at bugs.ruby-lang.org.

Constants

DecimalInteger

Decimal integer format, to be converted to Integer.

DecimalNumeric

Decimal integer/float number format, to be converted to Integer for integer format, Float for float format.

OctalInteger

Ruby/C like octal/hexadecimal/binary integer format, to be converted to Integer.

Version

The version string

Attributes

banner [W]

Heading banner preceding summary.

default_argv [RW]

Strings to be parsed in default.

program_name [W]

Program name to be emitted in error message and default banner, defaults to $0.

raise_unknown [RW]

Whether to raise at unknown option.

release [W]

Release code

require_exact [RW]

Whether to require that options match exactly (disallows providing abbreviated long option as short option).

set_banner [W]

Heading banner preceding summary.

set_program_name [W]

Program name to be emitted in error message and default banner, defaults to $0.

set_summary_indent [RW]

Indentation for summary. Must be String (or have + String method).

set_summary_width [RW]

Width for option list portion of summary. Must be Numeric.

summary_indent [RW]

Indentation for summary. Must be String (or have + String method).

summary_width [RW]

Width for option list portion of summary. Must be Numeric.

version [W]

Version

Public Class Methods

accept (*args, &blk)

See accept.

# File lib/optparse.rb, line 1233
def self.accept(*args, &blk) top.accept(*args, &blk) end
getopts (*args, symbolize_names: false)

See getopts.

# File lib/optparse.rb, line 1913
def self.getopts(*args, symbolize_names: false)
  new.getopts(*args, symbolize_names: symbolize_names)
end
inc (arg, default = nil)

Returns an incremented value of default according to arg.

# File lib/optparse.rb, line 1155
def self.inc(arg, default = nil)
  case arg
  when Integer
    arg.nonzero?
  when nil
    default.to_i + 1
  end
end
new (banner = nil, width = 32, indent = ' ' * 4) { |self| ... }

Initializes the instance and yields itself if called with a block.

banner

Banner message.

width

Summary width.

indent

Summary indent.

# File lib/optparse.rb, line 1178
def initialize(banner = nil, width = 32, indent = ' ' * 4)
  @stack = [DefaultList, List.new, List.new]
  @program_name = nil
  @banner = banner
  @summary_width = width
  @summary_indent = indent
  @default_argv = ARGV
  @require_exact = false
  @raise_unknown = true
  add_officious
  yield self if block_given?
end
reject (*args, &blk)

See reject.

# File lib/optparse.rb, line 1246
def self.reject(*args, &blk) top.reject(*args, &blk) end
show_version (*pkgs)

Shows version string in packages if Version is defined.

pkgs

package list

# File lib/optparse/version.rb, line 10
def show_version(*pkgs)
  progname = ARGV.options.program_name
  result = false
  show = proc do |klass, cname, version|
    str = "#{progname}"
    unless klass == ::Object and cname == :VERSION
      version = version.join(".") if Array === version
      str << ": #{klass}" unless klass == Object
      str << " version #{version}"
    end
    [:Release, :RELEASE].find do |rel|
      if klass.const_defined?(rel)
        str << " (#{klass.const_get(rel)})"
      end
    end
    puts str
    result = true
  end
  if pkgs.size == 1 and pkgs[0] == "all"
    self.search_const(::Object, /\AV(?:ERSION|ersion)\z/) do |klass, cname, version|
      unless cname[1] == ?e and klass.const_defined?(:Version)
        show.call(klass, cname.intern, version)
      end
    end
  else
    pkgs.each do |pkg|
      begin
        pkg = pkg.split(/::|\//).inject(::Object) {|m, c| m.const_get(c)}
        v = case
            when pkg.const_defined?(:Version)
              pkg.const_get(n = :Version)
            when pkg.const_defined?(:VERSION)
              pkg.const_get(n = :VERSION)
            else
              n = nil
              "unknown"
            end
        show.call(pkg, n, v)
      rescue NameError
      end
    end
  end
  result
end
terminate (arg = nil)

See terminate.

# File lib/optparse.rb, line 1208
def self.terminate(arg = nil)
  throw :terminate, arg
end
top ()

Returns the global top option list.

Do not use directly.

# File lib/optparse.rb, line 1218
def self.top() DefaultList end
with (*args, &block)

Initializes a new instance and evaluates the optional block in context of the instance. Arguments args are passed to new, see there for description of parameters.

This method is deprecated, its behavior corresponds to the older new method.

# File lib/optparse.rb, line 1146
def self.with(*args, &block)
  opts = new(*args)
  opts.instance_eval(&block)
  opts
end

Public Instance Methods

abort (mesg = $!)

Shows message with the program name then aborts.

mesg

Message, defaulted to +$!+.

See Kernel#abort.

Calls superclass method Kernel#abort 
# File lib/optparse.rb, line 1348
def abort(mesg = $!)
  super("#{program_name}: #{mesg}")
end
accept (*args, &blk)

Directs to accept specified class t. The argument string is passed to the block in which it should be converted to the desired class.

t

Argument class specifier, any object including Class.

pat

Pattern for argument, defaults to t if it responds to match.

accept(t, pat, &block)

# File lib/optparse.rb, line 1229
def accept(*args, &blk) top.accept(*args, &blk) end
additional_message (typ, opt)

Returns additional info.

# File lib/optparse.rb, line 1964
def additional_message(typ, opt)
  return unless typ and opt and defined?(DidYouMean::SpellChecker)
  all_candidates = []
  visit(:get_candidates, typ) do |candidates|
    all_candidates.concat(candidates)
  end
  all_candidates.select! {|cand| cand.is_a?(String) }
  checker = DidYouMean::SpellChecker.new(dictionary: all_candidates)
  DidYouMean.formatter.message_for(all_candidates & checker.correct(opt))
end
banner ()

Heading banner preceding summary.

base ()

Subject of on_tail.

# File lib/optparse.rb, line 1362
def base
  @stack[1]
end
candidate (word)

Return candidates for word.

# File lib/optparse.rb, line 1978
def candidate(word)
  list = []
  case word
  when '-'
    long = short = true
  when /\A--/
    word, arg = word.split(/=/, 2)
    argpat = Completion.regexp(arg, false) if arg and !arg.empty?
    long = true
  when /\A-/
    short = true
  end
  pat = Completion.regexp(word, long)
  visit(:each_option) do |opt|
    next unless Switch === opt
    opts = (long ? opt.long : []) + (short ? opt.short : [])
    opts = Completion.candidate(word, true, pat, &opts.method(:each)).map(&:first) if pat
    if /\A=/ =~ opt.arg
      opts.map! {|sw| sw + "="}
      if arg and CompletingHash === opt.pattern
        if opts = opt.pattern.candidate(arg, false, argpat)
          opts.map!(&:last)
        end
      end
    end
    list.concat(opts)
  end
  list
end
def_head_option
Alias for: define_head
def_option
Alias for: define
def_tail_option
Alias for: define_tail
define(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

# File lib/optparse.rb, line 1606
def define(*opts, &block)
  top.append(*(sw = make_switch(opts, block)))
  sw[0]
end
Also aliased as: def_option
define_by_keywords(options, method, **params)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

Defines options which set in to options for keyword parameters of method.

Parameters for each keywords are given as elements of params.

# File lib/optparse/kwargs.rb, line 15
def define_by_keywords(options, method, **params)
  method.parameters.each do |type, name|
    case type
    when :key, :keyreq
      op, cl = *(type == :key ? %w"[ ]" : ["", ""])
      define("--#{name}=#{op}#{name.upcase}#{cl}", *params[name]) do |o|
        options[name] = o
      end
    end
  end
  options
end
define_head(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

# File lib/optparse.rb, line 1627
def define_head(*opts, &block)
  top.prepend(*(sw = make_switch(opts, block)))
  sw[0]
end
Also aliased as: def_head_option
define_tail(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

# File lib/optparse.rb, line 1650
def define_tail(*opts, &block)
  base.append(*(sw = make_switch(opts, block)))
  sw[0]
end
Also aliased as: def_tail_option
environment (env = File.basename($0, '.*'), **keywords)

Parses environment variable env or its uppercase with splitting like a shell.

env defaults to the basename of the program.

# File lib/optparse.rb, line 2051
def environment(env = File.basename($0, '.*'), **keywords)
  env = ENV[env] || ENV[env.upcase] or return
  require 'shellwords'
  parse(*Shellwords.shellwords(env), **keywords)
end
getopts (*args, symbolize_names: false, **keywords)

Wrapper method for getopts.rb.

params = ARGV.getopts("ab:", "foo", "bar:", "zot:Z;zot option")
# params["a"] = true   # -a
# params["b"] = "1"    # -b1
# params["foo"] = "1"  # --foo
# params["bar"] = "x"  # --bar x
# params["zot"] = "z"  # --zot Z

Option symbolize_names (boolean) specifies whether returned Hash keys should be Symbols; defaults to false (use Strings).

params = ARGV.getopts("ab:", "foo", "bar:", "zot:Z;zot option", symbolize_names: true)
# params[:a] = true   # -a
# params[:b] = "1"    # -b1
# params[:foo] = "1"  # --foo
# params[:bar] = "x"  # --bar x
# params[:zot] = "z"  # --zot Z

# File lib/optparse.rb, line 1878
def getopts(*args, symbolize_names: false, **keywords)
  argv = Array === args.first ? args.shift : default_argv
  single_options, *long_options = *args

  result = {}

  single_options.scan(/(.)(:)?/) do |opt, val|
    if val
      result[opt] = nil
      define("-#{opt} VAL")
    else
      result[opt] = false
      define("-#{opt}")
    end
  end if single_options

  long_options.each do |arg|
    arg, desc = arg.split(';', 2)
    opt, val = arg.split(':', 2)
    if val
      result[opt] = val.empty? ? nil : val
      define("--#{opt}=#{result[opt] || "VAL"}", *[desc].compact)
    else
      result[opt] = false
      define("--#{opt}", *[desc].compact)
    end
  end

  parse_in_order(argv, result.method(:[]=), **keywords)
  symbolize_names ? result.transform_keys(&:to_sym) : result
end
help ()

Returns option summary string.

# File lib/optparse.rb, line 1407
def help; summarize("#{banner}".sub(/\n?\z/, "\n")) end
Also aliased as: to_s
inc (*args)

See self.inc

# File lib/optparse.rb, line 1167
def inc(*args)
  self.class.inc(*args)
end
load (filename = nil, **keywords)

Loads options from file names as filename. Does nothing when the file is not present. Returns whether successfully loaded.

filename defaults to basename of the program without suffix in a directory ~/.options, then the basename with ‘.options’ suffix under XDG and Haiku standard places.

The optional into keyword argument works exactly like that accepted in method parse.

# File lib/optparse.rb, line 2019
def load(filename = nil, **keywords)
  unless filename
    basename = File.basename($0, '.*')
    return true if load(File.expand_path(basename, '~/.options'), **keywords) rescue nil
    basename << ".options"
    return [
      # XDG
      ENV['XDG_CONFIG_HOME'],
      '~/.config',
      *ENV['XDG_CONFIG_DIRS']&.split(File::PATH_SEPARATOR),

      # Haiku
      '~/config/settings',
    ].any? {|dir|
      next if !dir or dir.empty?
      load(File.expand_path(basename, dir), **keywords) rescue nil
    }
  end
  begin
    parse(*File.readlines(filename, chomp: true), **keywords)
    true
  rescue Errno::ENOENT, Errno::ENOTDIR
    false
  end
end
make_switch(params, block = nil)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

# File lib/optparse.rb, line 1462
def make_switch(opts, block = nil)
  short, long, nolong, style, pattern, conv, not_pattern, not_conv, not_style = [], [], []
  ldesc, sdesc, desc, arg = [], [], []
  default_style = Switch::NoArgument
  default_pattern = nil
  klass = nil
  q, a = nil
  has_arg = false

  opts.each do |o|
    # argument class
    next if search(:atype, o) do |pat, c|
      klass = notwice(o, klass, 'type')
      if not_style and not_style != Switch::NoArgument
        not_pattern, not_conv = pat, c
      else
        default_pattern, conv = pat, c
      end
    end

    # directly specified pattern(any object possible to match)
    if (!(String === o || Symbol === o)) and o.respond_to?(:match)
      pattern = notwice(o, pattern, 'pattern')
      if pattern.respond_to?(:convert)
        conv = pattern.method(:convert).to_proc
      else
        conv = SPLAT_PROC
      end
      next
    end

    # anything others
    case o
    when Proc, Method
      block = notwice(o, block, 'block')
    when Array, Hash
      case pattern
      when CompletingHash
      when nil
        pattern = CompletingHash.new
        conv = pattern.method(:convert).to_proc if pattern.respond_to?(:convert)
      else
        raise ArgumentError, "argument pattern given twice"
      end
      o.each {|pat, *v| pattern[pat] = v.fetch(0) {pat}}
    when Module
      raise ArgumentError, "unsupported argument type: #{o}", ParseError.filter_backtrace(caller(4))
    when *ArgumentStyle.keys
      style = notwice(ArgumentStyle[o], style, 'style')
    when /^--no-([^\[\]=\s]*)(.+)?/
      q, a = $1, $2
      o = notwice(a ? Object : TrueClass, klass, 'type')
      not_pattern, not_conv = search(:atype, o) unless not_style
      not_style = (not_style || default_style).guess(arg = a) if a
      default_style = Switch::NoArgument
      default_pattern, conv = search(:atype, FalseClass) unless default_pattern
      ldesc << "--no-#{q}"
      (q = q.downcase).tr!('_', '-')
      long << "no-#{q}"
      nolong << q
    when /^--\[no-\]([^\[\]=\s]*)(.+)?/
      q, a = $1, $2
      o = notwice(a ? Object : TrueClass, klass, 'type')
      if a
        default_style = default_style.guess(arg = a)
        default_pattern, conv = search(:atype, o) unless default_pattern
      end
      ldesc << "--[no-]#{q}"
      (o = q.downcase).tr!('_', '-')
      long << o
      not_pattern, not_conv = search(:atype, FalseClass) unless not_style
      not_style = Switch::NoArgument
      nolong << "no-#{o}"
    when /^--([^\[\]=\s]*)(.+)?/
      q, a = $1, $2
      if a
        o = notwice(NilClass, klass, 'type')
        default_style = default_style.guess(arg = a)
        default_pattern, conv = search(:atype, o) unless default_pattern
      end
      ldesc << "--#{q}"
      (o = q.downcase).tr!('_', '-')
      long << o
    when /^-(\[\^?\]?(?:[^\\\]]|\\.)*\])(.+)?/
      q, a = $1, $2
      o = notwice(Object, klass, 'type')
      if a
        default_style = default_style.guess(arg = a)
        default_pattern, conv = search(:atype, o) unless default_pattern
      else
        has_arg = true
      end
      sdesc << "-#{q}"
      short << Regexp.new(q)
    when /^-(.)(.+)?/
      q, a = $1, $2
      if a
        o = notwice(NilClass, klass, 'type')
        default_style = default_style.guess(arg = a)
        default_pattern, conv = search(:atype, o) unless default_pattern
      end
      sdesc << "-#{q}"
      short << q
    when /^=/
      style = notwice(default_style.guess(arg = o), style, 'style')
      default_pattern, conv = search(:atype, Object) unless default_pattern
    else
      desc.push(o) if o && !o.empty?
    end
  end

  default_pattern, conv = search(:atype, default_style.pattern) unless default_pattern
  if !(short.empty? and long.empty?)
    if has_arg and default_style == Switch::NoArgument
      default_style = Switch::RequiredArgument
    end
    s = (style || default_style).new(pattern || default_pattern,
                                     conv, sdesc, ldesc, arg, desc, block)
  elsif !block
    if style or pattern
      raise ArgumentError, "no switch given", ParseError.filter_backtrace(caller)
    end
    s = desc
  else
    short << pattern
    s = (style || default_style).new(pattern,
                                     conv, nil, nil, arg, desc, block)
  end
  return s, short, long,
    (not_style.new(not_pattern, not_conv, sdesc, ldesc, nil, desc, block) if not_style),
    nolong
end
new () { |self| ... }

Pushes a new List.

If a block is given, yields self and returns the result of the block, otherwise returns self.

# File lib/optparse.rb, line 1372
def new
  @stack.push(List.new)
  if block_given?
    yield self
  else
    self
  end
end
on(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

# File lib/optparse.rb, line 1616
def on(*opts, &block)
  define(*opts, &block)
  self
end
on_head(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

The new option is added at the head of the summary.

# File lib/optparse.rb, line 1639
def on_head(*opts, &block)
  define_head(*opts, &block)
  self
end
on_tail(*params, &block)

Creates an option from the given parameters params. See Parameters for New Options.

The block, if given, is the handler for the created option. When the option is encountered during command-line parsing, the block is called with the argument given for the option, if any. See Option Handlers.

The new option is added at the tail of the summary.

# File lib/optparse.rb, line 1663
def on_tail(*opts, &block)
  define_tail(*opts, &block)
  self
end
order (*argv, **keywords, &nonopt)

Parses command line arguments argv in order. When a block is given, each non-option argument is yielded. When optional into keyword argument is provided, the parsed option values are stored there via []= method (so it can be Hash, or OpenStruct, or other similar object).

Returns the rest of argv left unparsed.

# File lib/optparse.rb, line 1692
def order(*argv, **keywords, &nonopt)
  argv = argv[0].dup if argv.size == 1 and Array === argv[0]
  order!(argv, **keywords, &nonopt)
end
order! (argv = default_argv, into: nil, **keywords, &nonopt)

Same as order, but removes switches destructively. Non-option arguments remain in argv.

# File lib/optparse.rb, line 1701
def order!(argv = default_argv, into: nil, **keywords, &nonopt)
  setter = ->(name, val) {into[name.to_sym] = val} if into
  parse_in_order(argv, setter, **keywords, &nonopt)
end
parse (*argv, **keywords)

Parses command line arguments argv in order when environment variable POSIXLY_CORRECT is set, and in permutation mode otherwise. When optional into keyword argument is provided, the parsed option values are stored there via []= method (so it can be Hash, or OpenStruct, or other similar object).

# File lib/optparse.rb, line 1842
def parse(*argv, **keywords)
  argv = argv[0].dup if argv.size == 1 and Array === argv[0]
  parse!(argv, **keywords)
end
parse! (argv = default_argv, **keywords)

Same as parse, but removes switches destructively. Non-option arguments remain in argv.

# File lib/optparse.rb, line 1851
def parse!(argv = default_argv, **keywords)
  if ENV.include?('POSIXLY_CORRECT')
    order!(argv, **keywords)
  else
    permute!(argv, **keywords)
  end
end
permute (*argv, **keywords)

Parses command line arguments argv in permutation mode and returns list of non-option arguments. When optional into keyword argument is provided, the parsed option values are stored there via []= method (so it can be Hash, or OpenStruct, or other similar object).

# File lib/optparse.rb, line 1819
def permute(*argv, **keywords)
  argv = argv[0].dup if argv.size == 1 and Array === argv[0]
  permute!(argv, **keywords)
end
permute! (argv = default_argv, **keywords)

Same as permute, but removes switches destructively. Non-option arguments remain in argv.

# File lib/optparse.rb, line 1828
def permute!(argv = default_argv, **keywords)
  nonopts = []
  order!(argv, **keywords, &nonopts.method(:<<))
  argv[0, 0] = nonopts
  argv
end
program_name ()

Program name to be emitted in error message and default banner, defaults to $0.

# File lib/optparse.rb, line 1290
def program_name
  @program_name || File.basename($0, '.*')
end
reject (*args, &blk)

Directs to reject specified class argument.

type

Argument class specifier, any object including Class.

reject(type)

# File lib/optparse.rb, line 1242
def reject(*args, &blk) top.reject(*args, &blk) end
release ()

Release code

# File lib/optparse.rb, line 1315
def release
  (defined?(@release) && @release) || (defined?(::Release) && ::Release) || (defined?(::RELEASE) && ::RELEASE)
end
remove ()

Removes the last List.

# File lib/optparse.rb, line 1384
def remove
  @stack.pop
end
separator (string)

Add separator in summary.

# File lib/optparse.rb, line 1672
def separator(string)
  top.append(string, nil, nil)
end
summarize (to = [], width = @summary_width, max = width - 1, indent = @summary_indent, &blk)

Puts option summary into to and returns to. Yields each line if a block is given.

to

Output destination, which must have method <<. Defaults to [].

width

Width of left side, defaults to @summary_width.

max

Maximum length allowed for left side, defaults to width - 1.

indent

Indentation, defaults to @summary_indent.

# File lib/optparse.rb, line 1397
def summarize(to = [], width = @summary_width, max = width - 1, indent = @summary_indent, &blk)
  nl = "\n"
  blk ||= proc {|l| to << (l.index(nl, -1) ? l : l + nl)}
  visit(:summarize, {}, {}, width, max, indent, &blk)
  to
end
terminate (arg = nil)

Terminates option parsing. Optional parameter arg is a string pushed back to be the first non-option argument.

# File lib/optparse.rb, line 1202
def terminate(arg = nil)
  self.class.terminate(arg)
end
to_a ()

Returns option summary list.

# File lib/optparse.rb, line 1436
def to_a; summarize("#{banner}".split(/^/)) end
to_s ()
Alias for: help
top ()

Subject of on / on_head, accept / reject

# File lib/optparse.rb, line 1355
def top
  @stack[-1]
end
ver ()

Returns version string from program_name, version and release.

# File lib/optparse.rb, line 1322
def ver
  if v = version
    str = +"#{program_name} #{[v].join('.')}"
    str << " (#{v})" if v = release
    str
  end
end
version ()

Version

# File lib/optparse.rb, line 1308
def version
  (defined?(@version) && @version) || (defined?(::Version) && ::Version)
end
warn (mesg = $!)

Shows warning message with the program name

mesg

Message, defaulted to +$!+.

See Kernel#warn.

Calls superclass method Kernel#warn 
# File lib/optparse.rb, line 1337
def warn(mesg = $!)
  super("#{program_name}: #{mesg}")
end