class GetoptLong

Class GetoptLong provides parsing both for options and for regular arguments.

Using GetoptLong, you can define options for your program. The program can then capture and respond to whatever options are included in the command that executes the program.

A simple example: file simple.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--number', '-n', GetoptLong::REQUIRED_ARGUMENT],
  ['--verbose', '-v', GetoptLong::OPTIONAL_ARGUMENT],
  ['--help', '-h', GetoptLong::NO_ARGUMENT]
)

If you are somewhat familiar with options, you may want to skip to this full example.

Options

A GetoptLong option has:

  • A string option name.

  • Zero or more string aliases for the name.

  • An option type.

Options may be defined by calling singleton method GetoptLong.new, which returns a new GetoptLong object. Options may then be processed by calling other methods such as GetoptLong#each.

Option Name and Aliases

In the array that defines an option, the first element is the string option name. Often the name takes the ‘long’ form, beginning with two hyphens.

The option name may have any number of aliases, which are defined by additional string elements.

The name and each alias must be of one of two forms:

  • Two hyphens, followed by one or more letters.

  • One hyphen, followed by a single letter.

File aliases.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', '-x', '--aaa', '-a', '-p', GetoptLong::NO_ARGUMENT]
)
options.each do |option, argument|
  p [option, argument]
end

An option may be cited by its name, or by any of its aliases; the parsed option always reports the name, not an alias:

$ ruby aliases.rb -a -p --xxx --aaa -x

Output:

["--xxx", ""]
["--xxx", ""]
["--xxx", ""]
["--xxx", ""]
["--xxx", ""]

An option may also be cited by an abbreviation of its name or any alias, as long as that abbreviation is unique among the options.

File abbrev.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::NO_ARGUMENT],
  ['--xyz', GetoptLong::NO_ARGUMENT]
)
options.each do |option, argument|
  p [option, argument]
end

Command line:

$ ruby abbrev.rb --xxx --xx --xyz --xy

Output:

["--xxx", ""]
["--xxx", ""]
["--xyz", ""]
["--xyz", ""]

This command line raises GetoptLong::AmbiguousOption:

$ ruby abbrev.rb --x

Repetition

An option may be cited more than once:

$ ruby abbrev.rb --xxx --xyz --xxx --xyz

Output:

["--xxx", ""]
["--xyz", ""]
["--xxx", ""]
["--xyz", ""]

Treating Remaining Options as Arguments

A option-like token that appears anywhere after the token -- is treated as an ordinary argument, and is not processed as an option:

$ ruby abbrev.rb --xxx --xyz -- --xxx --xyz

Output:

["--xxx", ""]
["--xyz", ""]

Option Types

Each option definition includes an option type, which controls whether the option takes an argument.

File types.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', GetoptLong::NO_ARGUMENT]
)
options.each do |option, argument|
  p [option, argument]
end

Note that an option type has to do with the option argument (whether it is required, optional, or forbidden), not with whether the option itself is required.

Option with Required Argument

An option of type GetoptLong::REQUIRED_ARGUMENT must be followed by an argument, which is associated with that option:

$ ruby types.rb --xxx foo

Output:

["--xxx", "foo"]

If the option is not last, its argument is whatever follows it (even if the argument looks like another option):

$ ruby types.rb --xxx --yyy

Output:

["--xxx", "--yyy"]

If the option is last, an exception is raised:

$ ruby types.rb
# Raises GetoptLong::MissingArgument

Option with Optional Argument

An option of type GetoptLong::OPTIONAL_ARGUMENT may be followed by an argument, which if given is associated with that option.

If the option is last, it does not have an argument:

$ ruby types.rb --yyy

Output:

["--yyy", ""]

If the option is followed by another option, it does not have an argument:

$ ruby types.rb --yyy --zzz

Output:

["--yyy", ""]
["--zzz", ""]

Otherwise the option is followed by its argument, which is associated with that option:

$ ruby types.rb --yyy foo

Output:

["--yyy", "foo"]

Option with No Argument

An option of type GetoptLong::NO_ARGUMENT takes no argument:

ruby types.rb --zzz foo

Output:

["--zzz", ""]

ARGV

You can process options either with method each and a block, or with method get.

During processing, each found option is removed, along with its argument if there is one. After processing, each remaining element was neither an option nor the argument for an option.

File argv.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', GetoptLong::NO_ARGUMENT]
)
puts "Original ARGV: #{ARGV}"
options.each do |option, argument|
  p [option, argument]
end
puts "Remaining ARGV: #{ARGV}"

Command line:

$ ruby argv.rb --xxx Foo --yyy Bar Baz --zzz Bat Bam

Output:

Original ARGV: ["--xxx", "Foo", "--yyy", "Bar", "Baz", "--zzz", "Bat", "Bam"]
["--xxx", "Foo"]
["--yyy", "Bar"]
["--zzz", ""]
Remaining ARGV: ["Baz", "Bat", "Bam"]

Ordering

There are three settings that control the way the options are interpreted:

  • PERMUTE.

  • REQUIRE_ORDER.

  • RETURN_IN_ORDER.

The initial setting for a new GetoptLong object is REQUIRE_ORDER if environment variable POSIXLY_CORRECT is defined, PERMUTE otherwise.

PERMUTE Ordering

In the PERMUTE ordering, options and other, non-option, arguments may appear in any order and any mixture.

File permute.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', GetoptLong::NO_ARGUMENT]
)
puts "Original ARGV: #{ARGV}"
options.each do |option, argument|
  p [option, argument]
end
puts "Remaining ARGV: #{ARGV}"

Command line:

$ ruby permute.rb Foo --zzz Bar --xxx Baz --yyy Bat Bam --xxx Bag Bah

Output:

Original ARGV: ["Foo", "--zzz", "Bar", "--xxx", "Baz", "--yyy", "Bat", "Bam", "--xxx", "Bag", "Bah"]
["--zzz", ""]
["--xxx", "Baz"]
["--yyy", "Bat"]
["--xxx", "Bag"]
Remaining ARGV: ["Foo", "Bar", "Bam", "Bah"]

REQUIRE_ORDER Ordering

In the REQUIRE_ORDER ordering, all options precede all non-options; that is, each word after the first non-option word is treated as a non-option word (even if it begins with a hyphen).

File require_order.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', GetoptLong::NO_ARGUMENT]
)
options.ordering = GetoptLong::REQUIRE_ORDER
puts "Original ARGV: #{ARGV}"
options.each do |option, argument|
  p [option, argument]
end
puts "Remaining ARGV: #{ARGV}"

Command line:

$ ruby require_order.rb --xxx Foo Bar --xxx Baz --yyy Bat -zzz

Output:

Original ARGV: ["--xxx", "Foo", "Bar", "--xxx", "Baz", "--yyy", "Bat", "-zzz"]
["--xxx", "Foo"]
Remaining ARGV: ["Bar", "--xxx", "Baz", "--yyy", "Bat", "-zzz"]

RETURN_IN_ORDER Ordering

In the RETURN_IN_ORDER ordering, every word is treated as an option. A word that begins with a hyphen (or two) is treated in the usual way; a word word that does not so begin is treated as an option whose name is an empty string, and whose value is word.

File return_in_order.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', GetoptLong::NO_ARGUMENT]
)
options.ordering = GetoptLong::RETURN_IN_ORDER
puts "Original ARGV: #{ARGV}"
options.each do |option, argument|
  p [option, argument]
end
puts "Remaining ARGV: #{ARGV}"

Command line:

$ ruby return_in_order.rb Foo --xxx Bar Baz --zzz Bat Bam

Output:

Original ARGV: ["Foo", "--xxx", "Bar", "Baz", "--zzz", "Bat", "Bam"]
["", "Foo"]
["--xxx", "Bar"]
["", "Baz"]
["--zzz", ""]
["", "Bat"]
["", "Bam"]
Remaining ARGV: []

Full Example

File fibonacci.rb:

require 'getoptlong'

options = GetoptLong.new(
  ['--number', '-n', GetoptLong::REQUIRED_ARGUMENT],
  ['--verbose', '-v', GetoptLong::OPTIONAL_ARGUMENT],
  ['--help', '-h', GetoptLong::NO_ARGUMENT]
)

def help(status = 0)
  puts <<~HELP
    Usage:

      -n n, --number n:
        Compute Fibonacci number for n.
      -v [boolean], --verbose [boolean]:
        Show intermediate results; default is 'false'.
      -h, --help:
        Show this help.
  HELP
  exit(status)
end

def print_fibonacci (number)
  return 0 if number == 0
  return 1 if number == 1 or number == 2
  i = 0
  j = 1
  (2..number).each do
    k = i + j
    i = j
    j = k
    puts j if @verbose
  end
  puts j unless @verbose
end

options.each do |option, argument|
  case option
  when '--number'
    @number = argument.to_i
  when '--verbose'
    @verbose = if argument.empty?
      true
    elsif argument.match(/true/i)
      true
    elsif argument.match(/false/i)
      false
    else
      puts '--verbose argument must be true or false'
      help(255)
    end
  when '--help'
    help
  end
end

unless @number
  puts 'Option --number is required.'
  help(255)
end

print_fibonacci(@number)

Command line:

$ ruby fibonacci.rb

Output:

Option --number is required.
Usage:

  -n n, --number n:
    Compute Fibonacci number for n.
  -v [boolean], --verbose [boolean]:
    Show intermediate results; default is 'false'.
  -h, --help:
    Show this help.

Command line:

$ ruby fibonacci.rb --number

Raises GetoptLong::MissingArgument:

fibonacci.rb: option `--number' requires an argument

Command line:

$ ruby fibonacci.rb --number 6

Output:

8

Command line:

$ ruby fibonacci.rb --number 6 --verbose

Output:

1
2
3
5
8

Command line:

$ ruby fibonacci.rb –number 6 –verbose yes

Output:

--verbose argument must be true or false
Usage:

  -n n, --number n:
    Compute Fibonacci number for n.
  -v [boolean], --verbose [boolean]:
    Show intermediate results; default is 'false'.
  -h, --help:
    Show this help.

Constants

ARGUMENT_FLAGS

Argument flags.

ORDERINGS

Orderings.

STATUS_TERMINATED
VERSION

Version.

Attributes

error[R]

Returns whether option processing has failed.

error?[R]

Returns whether option processing has failed.

ordering[R]

Returns the ordering setting.

quiet[RW]

Sets quiet mode and returns the given argument:

  • When false or nil, error messages are written to $stdout.

  • Otherwise, error messages are not written.

quiet?[RW]

Sets quiet mode and returns the given argument:

  • When false or nil, error messages are written to $stdout.

  • Otherwise, error messages are not written.

Public Class Methods

new(*arguments) click to toggle source

Returns a new GetoptLong object based on the given arguments. See Options.

Example:

require 'getoptlong'

options = GetoptLong.new(
  ['--number', '-n', GetoptLong::REQUIRED_ARGUMENT],
  ['--verbose', '-v', GetoptLong::OPTIONAL_ARGUMENT],
  ['--help', '-h', GetoptLong::NO_ARGUMENT]
)

Raises an exception if:

  • Any of arguments is not an array.

  • Any option name or alias is not a string.

  • Any option type is invalid.

# File getoptlong.rb, line 412
def initialize(*arguments)
  #
  # Current ordering.
  #
  if ENV.include?('POSIXLY_CORRECT')
    @ordering = REQUIRE_ORDER
  else
    @ordering = PERMUTE
  end

  #
  # Hash table of option names.
  # Keys of the table are option names, and their values are canonical
  # names of the options.
  #
  @canonical_names = Hash.new

  #
  # Hash table of argument flags.
  # Keys of the table are option names, and their values are argument
  # flags of the options.
  #
  @argument_flags = Hash.new

  #
  # Whether error messages are output to $stderr.
  #
  @quiet = false

  #
  # Status code.
  #
  @status = STATUS_YET

  #
  # Error code.
  #
  @error = nil

  #
  # Error message.
  #
  @error_message = nil

  #
  # Rest of catenated short options.
  #
  @rest_singles = ''

  #
  # List of non-option-arguments.
  # Append them to ARGV when option processing is terminated.
  #
  @non_option_arguments = Array.new

  if 0 < arguments.length
    set_options(*arguments)
  end
end

Public Instance Methods

each() { |option_name, option_argument| ... } click to toggle source

Calls the given block with each option; each option is a 2-element array containing:

  • The option name (the name itself, not an alias).

  • The option value.

Example:

require 'getoptlong'

options = GetoptLong.new(
  ['--xxx', '-x', GetoptLong::REQUIRED_ARGUMENT],
  ['--yyy', '-y', GetoptLong::OPTIONAL_ARGUMENT],
  ['--zzz', '-z',GetoptLong::NO_ARGUMENT]
)
puts "Original ARGV: #{ARGV}"
options.each do |option, argument|
  p [option, argument]
end
puts "Remaining ARGV: #{ARGV}"

Command line:

ruby each.rb -xxx Foo -x Bar --yyy Baz -y Bat --zzz

Output:

Original ARGV: ["-xxx", "Foo", "-x", "Bar", "--yyy", "Baz", "-y", "Bat", "--zzz"]
["--xxx", "xx"]
["--xxx", "Bar"]
["--yyy", "Baz"]
["--yyy", "Bat"]
["--zzz", ""]
Remaining ARGV: ["Foo"]
# File getoptlong.rb, line 859
def each
  loop do
    option_name, option_argument = get_option
    break if option_name == nil
    yield option_name, option_argument
  end
end
Also aliased as: each_option
each_option()
Alias for: each
error_message() click to toggle source

Return the appropriate error message in POSIX-defined format. If no error has occurred, returns nil.

# File getoptlong.rb, line 662
def error_message
  return @error_message
end
get() click to toggle source

Returns the next option as a 2-element array containing:

  • The option name (the name itself, not an alias).

  • The option value.

Returns nil if there are no more options.

# File getoptlong.rb, line 674
def get
  option_name, option_argument = nil, ''

  #
  # Check status.
  #
  return nil if @error != nil
  case @status
  when STATUS_YET
    @status = STATUS_STARTED
  when STATUS_TERMINATED
    return nil
  end

  #
  # Get next option argument.
  #
  if 0 < @rest_singles.length
    argument = '-' + @rest_singles
  elsif (ARGV.length == 0)
    terminate
    return nil
  elsif @ordering == PERMUTE
    while 0 < ARGV.length && ARGV[0] !~ /\A-./
      @non_option_arguments.push(ARGV.shift)
    end
    if ARGV.length == 0
      terminate
      return nil
    end
    argument = ARGV.shift
  elsif @ordering == REQUIRE_ORDER
    if (ARGV[0] !~ /\A-./)
      terminate
      return nil
    end
    argument = ARGV.shift
  else
    argument = ARGV.shift
  end

  #
  # Check the special argument `--'.
  # `--' indicates the end of the option list.
  #
  if argument == '--' && @rest_singles.length == 0
    terminate
    return nil
  end

  #
  # Check for long and short options.
  #
  if argument =~ /\A(--[^=]+)/ && @rest_singles.length == 0
    #
    # This is a long style option, which start with `--'.
    #
    pattern = $1
    if @canonical_names.include?(pattern)
      option_name = pattern
    else
      #
      # The option `option_name' is not registered in `@canonical_names'.
      # It may be an abbreviated.
      #
      matches = []
      @canonical_names.each_key do |key|
        if key.index(pattern) == 0
          option_name = key
          matches << key
        end
      end
      if 2 <= matches.length
        set_error(AmbiguousOption, "option `#{argument}' is ambiguous between #{matches.join(', ')}")
      elsif matches.length == 0
        set_error(InvalidOption, "unrecognized option `#{argument}'")
      end
    end

    #
    # Check an argument to the option.
    #
    if @argument_flags[option_name] == REQUIRED_ARGUMENT
      if argument =~ /=(.*)/m
        option_argument = $1
      elsif 0 < ARGV.length
        option_argument = ARGV.shift
      else
        set_error(MissingArgument,
                  "option `#{argument}' requires an argument")
      end
    elsif @argument_flags[option_name] == OPTIONAL_ARGUMENT
      if argument =~ /=(.*)/m
        option_argument = $1
      elsif 0 < ARGV.length && ARGV[0] !~ /\A-./
        option_argument = ARGV.shift
      else
        option_argument = ''
      end
    elsif argument =~ /=(.*)/m
      set_error(NeedlessArgument,
                "option `#{option_name}' doesn't allow an argument")
    end

  elsif argument =~ /\A(-(.))(.*)/m
    #
    # This is a short style option, which start with `-' (not `--').
    # Short options may be catenated (e.g. `-l -g' is equivalent to
    # `-lg').
    #
    option_name, ch, @rest_singles = $1, $2, $3

    if @canonical_names.include?(option_name)
      #
      # The option `option_name' is found in `@canonical_names'.
      # Check its argument.
      #
      if @argument_flags[option_name] == REQUIRED_ARGUMENT
        if 0 < @rest_singles.length
          option_argument = @rest_singles
          @rest_singles = ''
        elsif 0 < ARGV.length
          option_argument = ARGV.shift
        else
          # 1003.2 specifies the format of this message.
          set_error(MissingArgument, "option requires an argument -- #{ch}")
        end
      elsif @argument_flags[option_name] == OPTIONAL_ARGUMENT
        if 0 < @rest_singles.length
          option_argument = @rest_singles
          @rest_singles = ''
        elsif 0 < ARGV.length && ARGV[0] !~ /\A-./
          option_argument = ARGV.shift
        else
          option_argument = ''
        end
      end
    else
      #
      # This is an invalid option.
      # 1003.2 specifies the format of this message.
      #
      if ENV.include?('POSIXLY_CORRECT')
        set_error(InvalidOption, "invalid option -- #{ch}")
      else
        set_error(InvalidOption, "invalid option -- #{ch}")
      end
    end
  else
    #
    # This is a non-option argument.
    # Only RETURN_IN_ORDER fell into here.
    #
    return '', argument
  end

  return @canonical_names[option_name], option_argument
end
Also aliased as: get_option
get_option()
Alias for: get
ordering=(ordering) click to toggle source

Sets the ordering; see Ordering; returns the new ordering.

If the given ordering is PERMUTE and environment variable POSIXLY_CORRECT is defined, sets the ordering to REQUIRE_ORDER; otherwise sets the ordering to ordering:

options = GetoptLong.new
options.ordering == GetoptLong::PERMUTE # => true
options.ordering = GetoptLong::RETURN_IN_ORDER
options.ordering == GetoptLong::RETURN_IN_ORDER # => true
ENV['POSIXLY_CORRECT'] = 'true'
options.ordering = GetoptLong::PERMUTE
options.ordering == GetoptLong::REQUIRE_ORDER # => true

Raises an exception if ordering is invalid.

# File getoptlong.rb, line 489
def ordering=(ordering)
  #
  # The method is failed if option processing has already started.
  #
  if @status != STATUS_YET
    set_error(ArgumentError, "argument error")
    raise RuntimeError,
      "invoke ordering=, but option processing has already started"
  end

  #
  # Check ordering.
  #
  if !ORDERINGS.include?(ordering)
    raise ArgumentError, "invalid ordering `#{ordering}'"
  end
  if ordering == PERMUTE && ENV.include?('POSIXLY_CORRECT')
    @ordering = REQUIRE_ORDER
  else
    @ordering = ordering
  end
end
set_options(*arguments) click to toggle source

Replaces existing options with those given by arguments, which have the same form as the arguments to ::new; returns self.

Raises an exception if option processing has begun.

# File getoptlong.rb, line 524
def set_options(*arguments)
  #
  # The method is failed if option processing has already started.
  #
  if @status != STATUS_YET
    raise RuntimeError,
      "invoke set_options, but option processing has already started"
  end

  #
  # Clear tables of option names and argument flags.
  #
  @canonical_names.clear
  @argument_flags.clear

  arguments.each do |arg|
    if !arg.is_a?(Array)
     raise ArgumentError, "the option list contains non-Array argument"
    end

    #
    # Find an argument flag and it set to `argument_flag'.
    #
    argument_flag = nil
    arg.each do |i|
      if ARGUMENT_FLAGS.include?(i)
        if argument_flag != nil
          raise ArgumentError, "too many argument-flags"
        end
        argument_flag = i
      end
    end

    raise ArgumentError, "no argument-flag" if argument_flag == nil

    canonical_name = nil
    arg.each do |i|
      #
      # Check an option name.
      #
      next if i == argument_flag
      begin
        if !i.is_a?(String) || i !~ /\A-([^-]|-.+)\z/
          raise ArgumentError, "an invalid option `#{i}'"
        end
        if (@canonical_names.include?(i))
          raise ArgumentError, "option redefined `#{i}'"
        end
      rescue
        @canonical_names.clear
        @argument_flags.clear
        raise
      end

      #
      # Register the option (`i') to the `@canonical_names' and
      # `@canonical_names' Hashes.
      #
      if canonical_name == nil
        canonical_name = i
      end
      @canonical_names[i] = canonical_name
      @argument_flags[i] = argument_flag
    end
    raise ArgumentError, "no option name" if canonical_name == nil
  end
  return self
end
terminate() click to toggle source

Terminate option processing; returns nil if processing has already terminated; otherwise returns self.

# File getoptlong.rb, line 612
def terminate
  return nil if @status == STATUS_TERMINATED
  raise RuntimeError, "an error has occurred" if @error != nil

  @status = STATUS_TERMINATED
  @non_option_arguments.reverse_each do |argument|
    ARGV.unshift(argument)
  end

  @canonical_names = nil
  @argument_flags = nil
  @rest_singles = nil
  @non_option_arguments = nil

  return self
end
terminated?() click to toggle source

Returns true if option processing has terminated, false otherwise.

# File getoptlong.rb, line 632
def terminated?
  return @status == STATUS_TERMINATED
end

Protected Instance Methods

set_error(type, message) click to toggle source

Set an error (a protected method).

# File getoptlong.rb, line 639
def set_error(type, message)
  $stderr.print("#{$0}: #{message}\n") if !@quiet

  @error = type
  @error_message = message
  @canonical_names = nil
  @argument_flags = nil
  @rest_singles = nil
  @non_option_arguments = nil

  raise type, message
end