OptionParser

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:

  • Date – Anything accepted by Date.parse

  • DateTime – Anything accepted by DateTime.parse

  • Time – Anything accepted by Time.httpdate or Time.parse

  • URI – Anything accepted by URI.parse

  • Shellwords – Anything accepted by Shellwords.shellwords

  • String – Any non-empty string

  • Integer – Any integer. Will convert octal. (e.g. 124, -3, 040)

  • Float – Any float. (e.g. 10, 3.14, -100E+13)

  • Numeric – Any integer, float, or rational (1, 3.4, 1/3)

  • DecimalInteger – Like Integer, but no octal format.

  • OctalInteger – Like Integer, but no decimal format.

  • DecimalNumeric – Decimal integer or float.

  • TrueClass – Accepts '+, yes, true, -, no, false' and defaults as true

  • FalseClass – Same as TrueClass, but defaults to false

  • Array – Strings separated by ',' (e.g. 1,2,3)

  • Regexp – Regular expressions. Also includes options.

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'

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

p params

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 should be enough to learn how to use this class. If you have any questions, file a ticket at bugs.ruby-lang.org.


Constants


Decimal integer format, to be converted to Integer.

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

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

No documentation available
No documentation available

Attributes


Write

Heading banner preceding summary.

Read & Write

Strings to be parsed in default.

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

Write

Release code

Read & Write

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

Heading banner preceding summary.

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

Read & Write

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

Read & Write

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

Read & Write

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

Read & Write

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

Class Methods


See accept.

No documentation available

See getopts.

Returns an incremented value of default according to arg.

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

banner

Banner message.

width

Summary width.

indent

Summary indent.

See reject.

No documentation available
No documentation available
No documentation available
::
No documentation available

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.

Instance Methods


No documentation available

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)

Returns additional info.

Heading banner preceding summary.

Subject of on_tail.

No documentation available

Completes shortened long style option switch and returns pair of canonical switch and switch descriptor OptionParser::Switch.

typ

Searching table.

opt

Searching key.

icase

Search case insensitive if true.

pat

Optional pattern for completion.

No documentation available
No documentation available
No documentation available
No documentation available

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

env defaults to the basename of the program.

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

Returns option summary string.

No documentation available

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.

Creates an OptionParser::Switch from the parameters. The parsed argument value is passed to the given block, where it can be processed.

See at the beginning of OptionParser for some full examples.

params can include the following elements:

Argument style:

One of the following:

:NONE, :REQUIRED, :OPTIONAL
Argument pattern:

Acceptable option argument format, must be pre-defined with OptionParser.accept or OptionParser#accept, or Regexp. This can appear once or assigned as String if not present, otherwise causes an ArgumentError. Examples:

Float, Time, Array
Possible argument values:

Hash or Array.

[:text, :binary, :auto]
%w[iso-2022-jp shift_jis euc-jp utf8 binary]
{ "jis" => "iso-2022-jp", "sjis" => "shift_jis" }
Long style switch:

Specifies a long style switch which takes a mandatory, optional or no argument. It's a string of the following form:

"--switch=MANDATORY" or "--switch MANDATORY"
"--switch[=OPTIONAL]"
"--switch"
Short style switch:

Specifies short style switch which takes a mandatory, optional or no argument. It's a string of the following form:

"-xMANDATORY"
"-x[OPTIONAL]"
"-x"

There is also a special form which matches character range (not full set of regular expression):

"-[a-z]MANDATORY"
"-[a-z][OPTIONAL]"
"-[a-z]"
Argument style and description:

Instead of specifying mandatory or optional arguments directly in the switch parameter, this separate parameter can be used.

"=MANDATORY"
"=[OPTIONAL]"
Description:

Description string for the option.

"Run verbosely"

If you give multiple description strings, each string will be printed line by line.

Handler:

Handler for the parsed argument value. Either give a block or pass a Proc or Method as an argument.

Pushes a new List.

Checks if an argument is given twice, in which case an ArgumentError is raised. Called from OptionParser#switch only.

obj

New argument.

prv

Previously specified argument.

msg

Exception message.

Add option switch and handler. See make_switch for an explanation of parameters.

Add option switch like with on, but at head of summary.

Add option switch like with on, but at tail of summary.

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.

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

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).

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

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).

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

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

Directs to reject specified class argument.

t

Argument class specifier, any object including Class.

reject(t)

Release code

Removes the last List.

Searches key in @stack for id hash and returns or yields the result.

Add separator in summary.

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.

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

Returns option summary list.

An alias for help

Subject of on / on_head, accept / reject

Returns version string from program_name, version and release.

Traverses @stack, sending each element method id with args and block.

No documentation available