class GetoptLong

The GetoptLong class allows you to parse command line options similarly to the GNU getopt_long() C library call. Note, however, that GetoptLong is a pure Ruby implementation.

GetoptLong allows for POSIX-style options like --file as well as single letter options like -f

The empty option -- (two minus symbols) is used to end option processing. This can be particularly important if options have optional arguments.

Here is a simple example of usage:

require 'getoptlong'

opts = GetoptLong.new(
  [ '--help', '-h', GetoptLong::NO_ARGUMENT ],
  [ '--repeat', '-n', GetoptLong::REQUIRED_ARGUMENT ],
  [ '--name', GetoptLong::OPTIONAL_ARGUMENT ]
)

dir = nil
name = nil
repetitions = 1
opts.each do |opt, arg|
  case opt
    when '--help'
      puts <<-EOF
hello [OPTION] ... DIR

-h, --help:
   show help

--repeat x, -n x:
   repeat x times

--name [name]:
   greet user by name, if name not supplied default is John

DIR: The directory in which to issue the greeting.
      EOF
    when '--repeat'
      repetitions = arg.to_i
    when '--name'
      if arg == ''
        name = 'John'
      else
        name = arg
      end
  end
end

if ARGV.length != 1
  puts "Missing dir argument (try --help)"
  exit 0
end

dir = ARGV.shift

Dir.chdir(dir)
for i in (1..repetitions)
  print "Hello"
  if name
    print ", #{name}"
  end
  puts
end

Example command line:

hello -n 6 --name -- /tmp

Constants

ARGUMENT_FLAGS: Argument flags.
ORDERINGS: Orderings.
STATUS_TERMINATED
VERSION: Version.

Attributes

error[R]

Examine whether an option processing is failed.

error?[R]

Examine whether an option processing is failed.

ordering[R]

Return ordering.

quiet[RW]

Set/Unset ‘quiet’ mode.

quiet?[RW]

Set/Unset ‘quiet’ mode.

Public Class Methods

new(*arguments) click to toggle source

Set up option processing.

The options to support are passed to new() as an array of arrays. Each sub-array contains any number of String option names which carry the same meaning, and one of the following flags:

GetoptLong::NO_ARGUMENT: Option does not take an argument.
GetoptLong::REQUIRED_ARGUMENT: Option always takes an argument.
GetoptLong::OPTIONAL_ARGUMENT: Option may or may not take an argument.

The first option name is considered to be the preferred (canonical) name. Other than that, the elements of each sub-array can be in any order.

# File getoptlong.rb, line 132
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

Iterator version of ‘get’.

The block is called repeatedly with two arguments: The first is the option name. The second is the argument which followed it (if any). Example: (‘–opt’, ‘value’)

The option name is always converted to the first (preferred) name given in the original options to GetoptLong.new.

# File getoptlong.rb, line 604
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()

‘each_option’ is an alias of ‘each’.

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 415
def error_message
  return @error_message
end

get() click to toggle source

Get next option name and its argument, as an Array of two elements.

The option name is always converted to the first (preferred) name given in the original options to GetoptLong.new.

Example: [‘–option’, ‘value’]

Returns nil if the processing is complete (as determined by STATUS_TERMINATED).

# File getoptlong.rb, line 430
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()

‘get_option’ is an alias of ‘get’.

Alias for: get

ordering=(ordering) click to toggle source

Set the handling of the ordering of options and arguments. A RuntimeError is raised if option processing has already started.

The supplied value must be a member of GetoptLong::ORDERINGS. It alters the processing of options as follows:

REQUIRE_ORDER :

Options are required to occur before non-options.

Processing of options ends as soon as a word is encountered that has not been preceded by an appropriate option flag.

For example, if -a and -b are options which do not take arguments, parsing command line arguments of ‘-a one -b two’ would result in ‘one’, ‘-b’, ‘two’ being left in ARGV, and only (‘-a’, ”) being processed as an option/arg pair.

This is the default ordering, if the environment variable POSIXLY_CORRECT is set. (This is for compatibility with GNU getopt_long.)

PERMUTE :

Options can occur anywhere in the command line parsed. This is the default behavior.

Every sequence of words which can be interpreted as an option (with or without argument) is treated as an option; non-option words are skipped.

For example, if -a does not require an argument and -b optionally takes an argument, parsing ‘-a one -b two three’ would result in (‘-a’,”) and (‘-b’, ‘two’) being processed as option/arg pairs, and ‘one’,‘three’ being left in ARGV.

If the ordering is set to PERMUTE but the environment variable POSIXLY_CORRECT is set, REQUIRE_ORDER is used instead. This is for compatibility with GNU getopt_long.

RETURN_IN_ORDER :

All words on the command line are processed as options. Words not preceded by a short or long option flag are passed as arguments with an option of ” (empty string).

For example, if -a requires an argument but -b does not, a command line of ‘-a one -b two three’ would result in option/arg pairs of (‘-a’, ‘one’) (‘-b’, ”), (”, ‘two’), (”, ‘three’) being processed.

# File getoptlong.rb, line 241
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

Set options. Takes the same argument as GetoptLong.new.

Raises a RuntimeError if option processing has already started.

# File getoptlong.rb, line 274
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

Explicitly terminate option processing.

# File getoptlong.rb, line 361
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 381
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 388
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