tutorial - Documentation for Ruby 3.5 (original) (raw)

Why OptionParser? ↑

When a Ruby program executes, it captures its command-line arguments and options into variable ARGV. This simple program just prints its ARGV:

p ARGV

Execution, with arguments and options:

$ ruby argv.rb foo --bar --baz bat bam ["foo", "--bar", "--baz", "bat", "bam"]

The executing program is responsible for parsing and handling the command-line options.

OptionParser offers methods for parsing and handling those options.

With OptionParser, you can define options so that for each option:

The class also has method help, which displays automatically-generated help text.

Contents ↑

To Begin With ↑

To use OptionParser:

  1. Require the OptionParser code.
  2. Create an OptionParser object.
  3. Define one or more options.
  4. Parse the command line.

File basic.rb defines three options, -x, -y, and -z, each with a descriptive string, and each with a block.

require 'optparse'

parser = OptionParser.new

parser.on('-x', 'Whether to X') do |value| p ['x', value] end parser.on('-y', 'Whether to Y') do |value| p ['y', value] end parser.on('-z', 'Whether to Z') do |value| p ['z', value] end

p parser.parse!

From these defined options, the parser automatically builds help text:

$ ruby basic.rb --help Usage: basic [options] -x Whether to X -y Whether to Y -z Whether to Z

When an option is found during parsing, the block defined for the option is called with the argument value. An invalid option raises an exception.

Method parse!, which is used most often in this tutorial, removes from ARGV the options and arguments it finds, leaving other non-option arguments for the program to handle on its own. The method returns the possibly-reduced ARGV array.

Executions:

$ ruby basic.rb -x -z ["x", true] ["z", true] [] $ ruby basic.rb -z -y -x ["z", true] ["y", true] ["x", true] [] $ ruby basic.rb -x input_file.txt output_file.txt ["x", true] ["input_file.txt", "output_file.txt"] $ ruby basic.rb -a basic.rb:16:in '

': invalid option: -a (OptionParser::InvalidOption)

Defining Options ↑

A common way to define an option in OptionParser is with instance method OptionParser#on.

The method may be called with any number of arguments (whose order does not matter), and may also have a trailing optional keyword argument into.

The given arguments determine the characteristics of the new option. These may include:

Option Names ↑

You can give an option one or more names of two types:

Short Option Names ↑

A short option name consists of a hyphen and a single character.

File short_names.rb defines an option with a short name, -x, and an option with two short names (aliases, in effect) -y and -z.

require 'optparse' parser = OptionParser.new parser.on('-x', 'Short name') do |value| p ['x', value] end parser.on('-1', '-%', 'Two short names') do |value| p ['-1 or -%', value] end parser.parse!

Executions:

$ ruby short_names.rb --help Usage: short_names [options] -x Short name -1, -% Two short names $ ruby short_names.rb -x ["x", true] $ ruby short_names.rb -1 ["-1 or -%", true] $ ruby short_names.rb -% ["-1 or -%", true]

Multiple short names can “share” a hyphen:

$ ruby short_names.rb -x1% ["x", true] ["-1 or -%", true] ["-1 or -%", true]

Long Option Names ↑

A long option name consists of two hyphens and a one or more characters (usually two or more characters).

File long_names.rb defines an option with a long name, --xxx, and an option with two long names (aliases, in effect) --y1% and --z2#.

require 'optparse' parser = OptionParser.new parser.on('--xxx', 'Long name') do |value| p ['-xxx', value] end parser.on('--y1%', '--z2#', "Two long names") do |value| p ['--y1% or --z2#', value] end parser.parse!

Executions:

$ ruby long_names.rb --help Usage: long_names [options] --xxx Long name --y1%, --z2# Two long names $ ruby long_names.rb --xxx ["-xxx", true] $ ruby long_names.rb --y1% ["--y1% or --z2#", true] $ ruby long_names.rb --z2# ["--y1% or --z2#", true]

A long name may be defined with both positive and negative senses.

File long_with_negation.rb defines an option that has both senses.

require 'optparse' parser = OptionParser.new parser.on('--[no-]binary', 'Long name with negation') do |value| p [value, value.class] end parser.parse!

Executions:

$ ruby long_with_negation.rb --help Usage: long_with_negation [options] --[no-]binary Long name with negation $ ruby long_with_negation.rb --binary [true, TrueClass] $ ruby long_with_negation.rb --no-binary [false, FalseClass]

Mixing Option Names ↑

Many developers like to mix short and long option names, so that a short name is in effect an abbreviation of a long name.

File mixed_names.rb defines options that each have both a short and a long name.

require 'optparse' parser = OptionParser.new parser.on('-x', '--xxx', 'Short and long, no argument') do |value| p ['--xxx', value] end parser.on('-yYYY', '--yyy', 'Short and long, required argument') do |value| p ['--yyy', value] end parser.on('-z [ZZZ]', '--zzz', 'Short and long, optional argument') do |value| p ['--zzz', value] end parser.parse!

Executions:

$ ruby mixed_names.rb --help Usage: mixed_names [options] -x, --xxx Short and long, no argument -y, --yyyYYY Short and long, required argument -z, --zzz [ZZZ] Short and long, optional argument $ ruby mixed_names.rb -x ["--xxx", true] $ ruby mixed_names.rb --xxx ["--xxx", true] $ ruby mixed_names.rb -y mixed_names.rb:12:in '

': missing argument: -y (OptionParser::MissingArgument) $ ruby mixed_names.rb -y FOO ["--yyy", "FOO"] $ ruby mixed_names.rb --yyy mixed_names.rb:12:in '
': missing argument: --yyy (OptionParser::MissingArgument) $ ruby mixed_names.rb --yyy BAR ["--yyy", "BAR"] $ ruby mixed_names.rb -z ["--zzz", nil] $ ruby mixed_names.rb -z BAZ ["--zzz", "BAZ"] $ ruby mixed_names.rb --zzz ["--zzz", nil] $ ruby mixed_names.rb --zzz BAT ["--zzz", "BAT"]

Option Name Abbreviations ↑

By default, abbreviated option names on the command-line are allowed. An abbreviated name is valid if it is unique among abbreviated option names.

require 'optparse' parser = OptionParser.new parser.on('-n', '--dry-run',) do |value| p ['--dry-run', value] end parser.on('-d', '--draft',) do |value| p ['--draft', value] end parser.parse!

Executions:

$ ruby name_abbrev.rb --help Usage: name_abbrev [options] -n, --dry-run -d, --draft $ ruby name_abbrev.rb -n ["--dry-run", true] $ ruby name_abbrev.rb --dry-run ["--dry-run", true] $ ruby name_abbrev.rb -d ["--draft", true] $ ruby name_abbrev.rb --draft ["--draft", true] $ ruby name_abbrev.rb --d name_abbrev.rb:9:in '

': ambiguous option: --d (OptionParser::AmbiguousOption) $ ruby name_abbrev.rb --dr name_abbrev.rb:9:in '
': ambiguous option: --dr (OptionParser::AmbiguousOption) $ ruby name_abbrev.rb --dry ["--dry-run", true] $ ruby name_abbrev.rb --dra ["--draft", true]

You can disable abbreviation using method require_exact.

require 'optparse' parser = OptionParser.new parser.on('-n', '--dry-run',) do |value| p ['--dry-run', value] end parser.on('-d', '--draft',) do |value| p ['--draft', value] end parser.require_exact = true parser.parse!

Executions:

$ ruby no_abbreviation.rb --dry-ru no_abbreviation.rb:10:in '

': invalid option: --dry-ru (OptionParser::InvalidOption) $ ruby no_abbreviation.rb --dry-run ["--dry-run", true]

Option Arguments ↑

An option may take no argument, a required argument, or an optional argument.

Option with No Argument ↑

All the examples above define options with no argument.

Option with Required Argument ↑

Specify a required argument for an option by adding a dummy word to its name definition.

File required_argument.rb defines two options; each has a required argument because the name definition has a following dummy word.

require 'optparse' parser = OptionParser.new parser.on('-x XXX', '--xxx', 'Required argument via short name') do |value| p ['--xxx', value] end parser.on('-y', '--y YYY', 'Required argument via long name') do |value| p ['--yyy', value] end parser.parse!

When an option is found, the given argument is yielded.

Executions:

$ ruby required_argument.rb --help Usage: required_argument [options] -x, --xxx XXX Required argument via short name -y, --y YYY Required argument via long name $ ruby required_argument.rb -x AAA ["--xxx", "AAA"] $ ruby required_argument.rb -y BBB ["--yyy", "BBB"]

Omitting a required argument raises an error:

$ ruby required_argument.rb -x required_argument.rb:9:in '

': missing argument: -x (OptionParser::MissingArgument)

Option with Optional Argument ↑

Specify an optional argument for an option by adding a dummy word enclosed in square brackets to its name definition.

File optional_argument.rb defines two options; each has an optional argument because the name definition has a following dummy word in square brackets.

require 'optparse' parser = OptionParser.new parser.on('-x [XXX]', '--xxx', 'Optional argument via short name') do |value| p ['--xxx', value] end parser.on('-y', '--yyy [YYY]', 'Optional argument via long name') do |value| p ['--yyy', value] end parser.parse!

When an option with an argument is found, the given argument yielded.

Executions:

$ ruby optional_argument.rb --help Usage: optional_argument [options] -x, --xxx [XXX] Optional argument via short name -y, --yyy [YYY] Optional argument via long name $ ruby optional_argument.rb -x AAA ["--xxx", "AAA"] $ ruby optional_argument.rb -y BBB ["--yyy", "BBB"]

Omitting an optional argument does not raise an error.

Argument Abbreviations ↑

Specify an argument list as an Array or a Hash.

require 'optparse' parser = OptionParser.new parser.on('-x', '--xxx=VALUE', %w[ABC def], 'Argument abbreviations') do |value| p ['--xxx', value] end parser.on('-y', '--yyy=VALUE', {"abc"=>"XYZ", def: "FOO"}, 'Argument abbreviations') do |value| p ['--yyy', value] end parser.parse!

When an argument is abbreviated, the expanded argument yielded.

Executions:

$ ruby argument_abbreviation.rb --help Usage: argument_abbreviation [options] Usage: argument_abbreviation [options] -x, --xxx=VALUE Argument abbreviations -y, --yyy=VALUE Argument abbreviations $ ruby argument_abbreviation.rb --xxx A ["--xxx", "ABC"] $ ruby argument_abbreviation.rb --xxx c argument_abbreviation.rb:9:in '

': invalid argument: --xxx c (OptionParser::InvalidArgument) $ ruby argument_abbreviation.rb --yyy a --yyy d ["--yyy", "XYZ"] ["--yyy", "FOO"]

Argument Values ↑

Permissible argument values may be restricted either by specifying explicit values or by providing a pattern that the given value must match.

Explicit Argument Values ↑

You can specify argument values in either of two ways:

  • Specify values an array of strings.
  • Specify values a hash.
Explicit Values in Array ↑

You can specify explicit argument values in an array of strings. The argument value must be one of those strings, or an unambiguous abbreviation.

File explicit_array_values.rb defines options with explicit argument values.

require 'optparse' parser = OptionParser.new parser.on('-xXXX', ['foo', 'bar'], 'Values for required argument' ) do |value| p ['-x', value] end parser.on('-y [YYY]', ['baz', 'bat'], 'Values for optional argument') do |value| p ['-y', value] end parser.parse!

Executions:

$ ruby explicit_array_values.rb --help Usage: explicit_array_values [options] -xXXX Values for required argument -y [YYY] Values for optional argument $ ruby explicit_array_values.rb -x explicit_array_values.rb:9:in '

': missing argument: -x (OptionParser::MissingArgument) $ ruby explicit_array_values.rb -x foo ["-x", "foo"] $ ruby explicit_array_values.rb -x f ["-x", "foo"] $ ruby explicit_array_values.rb -x bar ["-x", "bar"] $ ruby explicit_array_values.rb -y ba explicit_array_values.rb:9:in '
': ambiguous argument: -y ba (OptionParser::AmbiguousArgument) $ ruby explicit_array_values.rb -x baz explicit_array_values.rb:9:in '
': invalid argument: -x baz (OptionParser::InvalidArgument)

Explicit Values in Hash ↑

You can specify explicit argument values in a hash with string keys. The value passed must be one of those keys, or an unambiguous abbreviation; the value yielded will be the value for that key.

File explicit_hash_values.rb defines options with explicit argument values.

require 'optparse' parser = OptionParser.new parser.on('-xXXX', {foo: 0, bar: 1}, 'Values for required argument' ) do |value| p ['-x', value] end parser.on('-y [YYY]', {baz: 2, bat: 3}, 'Values for optional argument') do |value| p ['-y', value] end parser.parse!

Executions:

$ ruby explicit_hash_values.rb --help Usage: explicit_hash_values [options] -xXXX Values for required argument -y [YYY] Values for optional argument $ ruby explicit_hash_values.rb -x explicit_hash_values.rb:9:in '

': missing argument: -x (OptionParser::MissingArgument) $ ruby explicit_hash_values.rb -x foo ["-x", 0] $ ruby explicit_hash_values.rb -x f ["-x", 0] $ ruby explicit_hash_values.rb -x bar ["-x", 1] $ ruby explicit_hash_values.rb -x baz explicit_hash_values.rb:9:in '
': invalid argument: -x baz (OptionParser::InvalidArgument) $ ruby explicit_hash_values.rb -y ["-y", nil] $ ruby explicit_hash_values.rb -y baz ["-y", 2] $ ruby explicit_hash_values.rb -y bat ["-y", 3] $ ruby explicit_hash_values.rb -y ba explicit_hash_values.rb:9:in '
': ambiguous argument: -y ba (OptionParser::AmbiguousArgument) $ ruby explicit_hash_values.rb -y bam ["-y", nil]

Argument Value Patterns ↑

You can restrict permissible argument values by specifying a Regexp that the given argument must match.

File matched_values.rb defines options with matched argument values.

require 'optparse' parser = OptionParser.new parser.on('--xxx XXX', /foo/i, 'Matched values') do |value| p ['--xxx', value] end parser.on('--yyy YYY', Integer, 'Check by range', 1..3) do |value| p ['--yyy', value] end parser.on('--zzz ZZZ', Integer, 'Check by list', [1, 3, 4]) do |value| p ['--zzz', value] end parser.parse!

Executions:

$ ruby matched_values.rb --help Usage: matched_values [options] --xxx XXX Matched values $ ruby matched_values.rb --xxx foo ["--xxx", "foo"] $ ruby matched_values.rb --xxx FOO ["--xxx", "FOO"] $ ruby matched_values.rb --xxx bar matched_values.rb:6:in '

': invalid argument: --xxx bar (OptionParser::InvalidArgument)

Keyword Argument into ↑

In parsing options, you can add keyword option into with a hash-like argument; each parsed option will be added as a name/value pair.

This is useful for:

  • Collecting options.
  • Checking for missing options.
  • Providing default values for options.

Collecting Options ↑

Use keyword argument into to collect options.

require 'optparse' parser = OptionParser.new parser.on('-x', '--xxx', 'Short and long, no argument') parser.on('-yYYY', '--yyy', 'Short and long, required argument') parser.on('-z [ZZZ]', '--zzz', 'Short and long, optional argument') options = {} parser.parse!(into: options) p options

Executions:

$ ruby collected_options.rb --help Usage: into [options] -x, --xxx Short and long, no argument -y, --yyyYYY Short and long, required argument -z, --zzz [ZZZ] Short and long, optional argument $ ruby collected_options.rb --xxx {:xxx=>true} $ ruby collected_options.rb --xxx --yyy FOO {:xxx=>true, :yyy=>"FOO"} $ ruby collected_options.rb --xxx --yyy FOO --zzz Bar {:xxx=>true, :yyy=>"FOO", :zzz=>"Bar"} $ ruby collected_options.rb --xxx --yyy FOO --yyy BAR {:xxx=>true, :yyy=>"BAR"}

Note in the last execution that the argument value for option --yyy was overwritten.

Checking for Missing Options ↑

Use the collected options to check for missing options.

require 'optparse' parser = OptionParser.new parser.on('-x', '--xxx', 'Short and long, no argument') parser.on('-yYYY', '--yyy', 'Short and long, required argument') parser.on('-z [ZZZ]', '--zzz', 'Short and long, optional argument') options = {} parser.parse!(into: options) required_options = [:xxx, :zzz] missing_options = required_options - options.keys unless missing_options.empty? fail "Missing required options: #{missing_options}" end

Executions:

$ ruby missing_options.rb --help Usage: missing_options [options] -x, --xxx Short and long, no argument -y, --yyyYYY Short and long, required argument -z, --zzz [ZZZ] Short and long, optional argument $ ruby missing_options.rb --yyy FOO missing_options.rb:11:in '

': Missing required options: [:xxx, :zzz] (RuntimeError)

Default Values for Options ↑

Initialize the into argument to define default values for options.

require 'optparse' parser = OptionParser.new parser.on('-x', '--xxx', 'Short and long, no argument') parser.on('-yYYY', '--yyy', 'Short and long, required argument') parser.on('-z [ZZZ]', '--zzz', 'Short and long, optional argument') options = {yyy: 'AAA', zzz: 'BBB'} parser.parse!(into: options) p options

Executions:

$ ruby default_values.rb --help Usage: default_values [options] -x, --xxx Short and long, no argument -y, --yyyYYY Short and long, required argument -z, --zzz [ZZZ] Short and long, optional argument $ ruby default_values.rb --yyy FOO {:yyy=>"FOO", :zzz=>"BBB"}

Argument Converters ↑

An option can specify that its argument is to be converted from the default String to an instance of another class. There are a number of built-in converters.

Example: File date.rb defines an option whose argument is to be converted to a Date object. The argument is converted by method Date#parse.

require 'optparse/date' parser = OptionParser.new parser.on('--date=DATE', Date) do |value| p [value, value.class] end parser.parse!

Executions:

$ ruby date.rb --date 2001-02-03 [#<Date: 2001-02-03 ((2451944j,0s,0n),+0s,2299161j)>, Date] $ ruby date.rb --date 20010203 [#<Date: 2001-02-03 ((2451944j,0s,0n),+0s,2299161j)>, Date] $ ruby date.rb --date "3rd Feb 2001" [#<Date: 2001-02-03 ((2451944j,0s,0n),+0s,2299161j)>, Date]

You can also define custom converters. See Argument Converters for both built-in and custom converters.

Help ↑

OptionParser makes automatically generated help text available.

The help text consists of:

  • A banner, showing the usage.
  • Option short and long names.
  • Option dummy argument names.
  • Option descriptions.

Example code:

require 'optparse' parser = OptionParser.new parser.on( '-x', '--xxx', 'Adipiscing elit. Aenean commodo ligula eget.', 'Aenean massa. Cum sociis natoque penatibus', ) parser.on( '-y', '--yyy YYY', 'Lorem ipsum dolor sit amet, consectetuer.' ) parser.on( '-z', '--zzz [ZZZ]', 'Et magnis dis parturient montes, nascetur', 'ridiculus mus. Donec quam felis, ultricies', 'nec, pellentesque eu, pretium quis, sem.', ) parser.parse!

The option names and dummy argument names are defined as described above.

The option description consists of the strings that are not themselves option names; An option can have more than one description string. Execution:

Usage: help [options] -x, --xxx Adipiscing elit. Aenean commodo ligula eget. Aenean massa. Cum sociis natoque penatibus -y, --yyy YYY Lorem ipsum dolor sit amet, consectetuer. -z, --zzz [ZZZ] Et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis, sem.

The program name is included in the default banner: Usage: #{program_name} [options]; you can change the program name.

require 'optparse' parser = OptionParser.new parser.program_name = 'help_program_name.rb' parser.parse!

Execution:

$ ruby help_program_name.rb --help Usage: help_program_name.rb [options]

You can also change the entire banner.

require 'optparse' parser = OptionParser.new parser.banner = "Usage: ruby help_banner.rb" parser.parse!

Execution:

$ ruby help_banner.rb --help Usage: ruby help_banner.rb

By default, the option names are indented 4 spaces and the width of the option-names field is 32 spaces.

You can change these values, along with the banner, by passing parameters to OptionParser.new.

require 'optparse' parser = OptionParser.new( 'ruby help_format.rb [options]', 20,
' ' * 2
) parser.on( '-x', '--xxx', 'Adipiscing elit. Aenean commodo ligula eget.', 'Aenean massa. Cum sociis natoque penatibus', ) parser.on( '-y', '--yyy YYY', 'Lorem ipsum dolor sit amet, consectetuer.' ) parser.on( '-z', '--zzz [ZZZ]', 'Et magnis dis parturient montes, nascetur', 'ridiculus mus. Donec quam felis, ultricies', 'nec, pellentesque eu, pretium quis, sem.', ) parser.parse!

Execution:

$ ruby help_format.rb --help ruby help_format.rb [options] -x, --xxx Adipiscing elit. Aenean commodo ligula eget. Aenean massa. Cum sociis natoque penatibus -y, --yyy YYY Lorem ipsum dolor sit amet, consectetuer. -z, --zzz [ZZZ] Et magnis dis parturient montes, nascetur ridiculus mus. Donec quam felis, ultricies nec, pellentesque eu, pretium quis, sem.

Top List and Base List ↑

An OptionParser object maintains a stack of OptionParser::List objects, each of which has a collection of zero or more options. It is unlikely that you’ll need to add or take away from that stack.

The stack includes:

When OptionParser builds its help text, the options in the top list precede those in the base list.

Methods for Defining Options ↑

Option-defining methods allow you to create an option, and also append/prepend it to the top list or append it to the base list.

Each of these next three methods accepts a sequence of parameter arguments and a block, creates an option object using method OptionParser#make_switch (see below), and returns the created option:

These next three methods are identical to the three above, except for their return values:

Though you may never need to call it directly, here’s the core method for defining an option:

  • Method OptionParser#make_switch accepts an array of parameters and a block. See Parameters for New Options. This method is unlike others here in that it:
    • Accepts an array of parameters; others accept a sequence of parameter arguments.
    • Returns an array containing the created option object, option names, and other values; others return either the created option object or the parser object self.

Parsing ↑

OptionParser has six instance methods for parsing.

Three have names ending with a “bang” (!):

  • parse!
  • order!
  • permute!

Each of these methods:

  • Accepts an optional array of string arguments argv; if not given, argv defaults to the value of OptionParser#default_argv, whose initial value is ARGV.
  • Accepts an optional keyword argument into (see Keyword Argument into).
  • Returns argv, possibly with some elements removed.

The three other methods have names not ending with a “bang”:

  • parse
  • order
  • permute

Each of these methods:

  • Accepts an array of string arguments or zero or more string arguments.
  • Accepts an optional keyword argument into and its value into. (see Keyword Argument into).
  • Returns argv, possibly with some elements removed.

Method parse! ↑

Method parse!:

  • Accepts an optional array of string arguments argv; if not given, argv defaults to the value of OptionParser#default_argv, whose initial value is ARGV.
  • Accepts an optional keyword argument into (see Keyword Argument into).
  • Returns argv, possibly with some elements removed.

The method processes the elements in argv beginning at argv[0], and ending, by default, at the end.

Otherwise processing ends and the method returns when:

  • The terminator argument -- is found; the terminator argument is removed before the return.
  • Environment variable POSIXLY_CORRECT is defined and a non-option argument is found; the non-option argument is not removed. Note that the value of that variable does not matter, as only its existence is checked.

File parse_bang.rb:

require 'optparse' parser = OptionParser.new parser.on('--xxx') do |value| p ['--xxx', value] end parser.on('--yyy YYY') do |value| p ['--yyy', value] end parser.on('--zzz [ZZZ]') do |value| p ['--zzz', value] end ret = parser.parse! puts "Returned: #{ret} (#{ret.class})"

Help:

$ ruby parse_bang.rb --help Usage: parse_bang [options] --xxx --yyy YYY --zzz [ZZZ]

Default behavior:

$ ruby parse_bang.rb input_file.txt output_file.txt --xxx --yyy FOO --zzz BAR ["--xxx", true] ["--yyy", "FOO"] ["--zzz", "BAR"] Returned: ["input_file.txt", "output_file.txt"] (Array)

Processing ended by terminator argument:

$ ruby parse_bang.rb input_file.txt output_file.txt --xxx --yyy FOO -- --zzz BAR ["--xxx", true] ["--yyy", "FOO"] Returned: ["input_file.txt", "output_file.txt", "--zzz", "BAR"] (Array)

Processing ended by non-option found when POSIXLY_CORRECT is defined:

$ POSIXLY_CORRECT=true ruby parse_bang.rb --xxx input_file.txt output_file.txt -yyy FOO ["--xxx", true] Returned: ["input_file.txt", "output_file.txt", "-yyy", "FOO"] (Array)

Method parse ↑

Method parse:

  • Accepts an array of string arguments or zero or more string arguments.
  • Accepts an optional keyword argument into and its value into. (see Keyword Argument into).
  • Returns argv, possibly with some elements removed.

If given an array ary, the method forms array argv as ary.dup. If given zero or more string arguments, those arguments are formed into array argv.

The method calls

parse!(argv, into: into)

Note that environment variable POSIXLY_CORRECT and the terminator argument -- are honored.

File parse.rb:

require 'optparse' parser = OptionParser.new parser.on('--xxx') do |value| p ['--xxx', value] end parser.on('--yyy YYY') do |value| p ['--yyy', value] end parser.on('--zzz [ZZZ]') do |value| p ['--zzz', value] end ret = parser.parse(ARGV) puts "Returned: #{ret} (#{ret.class})"

Help:

$ ruby parse.rb --help Usage: parse [options] --xxx --yyy YYY --zzz [ZZZ]

Default behavior:

$ ruby parse.rb input_file.txt output_file.txt --xxx --yyy FOO --zzz BAR ["--xxx", true] ["--yyy", "FOO"] ["--zzz", "BAR"] Returned: ["input_file.txt", "output_file.txt"] (Array)

Processing ended by terminator argument:

$ ruby parse.rb input_file.txt output_file.txt --xxx --yyy FOO -- --zzz BAR ["--xxx", true] ["--yyy", "FOO"] Returned: ["input_file.txt", "output_file.txt", "--zzz", "BAR"] (Array)

Processing ended by non-option found when POSIXLY_CORRECT is defined:

$ POSIXLY_CORRECT=true ruby parse.rb --xxx input_file.txt output_file.txt -yyy FOO ["--xxx", true] Returned: ["input_file.txt", "output_file.txt", "-yyy", "FOO"] (Array)

Method order! ↑

Calling method OptionParser#order! gives exactly the same result as calling method OptionParser#parse! with environment variable POSIXLY_CORRECT defined.

Method order ↑

Calling method OptionParser#order gives exactly the same result as calling method OptionParser#parse with environment variable POSIXLY_CORRECT defined.

Method permute! ↑

Calling method OptionParser#permute! gives exactly the same result as calling method OptionParser#parse! with environment variable POSIXLY_CORRECT not defined.

Method permute ↑

Calling method OptionParser#permute gives exactly the same result as calling method OptionParser#parse with environment variable POSIXLY_CORRECT not defined.