8 files changed, 78 insertions, 9 deletions
diff --git a/lib/optparse/ac.rb b/lib/optparse/ac.rb
index 9d520101aa..23fc740d10 100644
--- a/lib/optparse/ac.rb
+++ b/lib/optparse/ac.rb
@@ -1,7 +1,11 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 
+#
+# autoconf-like options.
+#
 class OptionParser::AC < OptionParser
+  # :stopdoc:
   private
 
   def _check_ac_args(name, block)
@@ -14,6 +18,7 @@ class OptionParser::AC < OptionParser
   end
 
   ARG_CONV = proc {|val| val.nil? ? true : val}
+  private_constant :ARG_CONV
 
   def _ac_arg_enable(prefix, name, help_string, block)
     _check_ac_args(name, block)
@@ -29,16 +34,27 @@ class OptionParser::AC < OptionParser
     enable
   end
 
+  # :startdoc:
+
   public
 
+  # Define <tt>--enable</tt> / <tt>--disable</tt> style option
+  #
+  # Appears as <tt>--enable-<i>name</i></tt> in help message.
   def ac_arg_enable(name, help_string, &block)
     _ac_arg_enable("enable", name, help_string, block)
   end
 
+  # Define <tt>--enable</tt> / <tt>--disable</tt> style option
+  #
+  # Appears as <tt>--disable-<i>name</i></tt> in help message.
   def ac_arg_disable(name, help_string, &block)
     _ac_arg_enable("disable", name, help_string, block)
   end
 
+  # Define <tt>--with</tt> / <tt>--without</tt> style option
+  #
+  # Appears as <tt>--with-<i>name</i></tt> in help message.
   def ac_arg_with(name, help_string, &block)
     _check_ac_args(name, block)
 
diff --git a/lib/optparse/date.rb b/lib/optparse/date.rb
index d6649c83f1..7bbf12b77f 100644
--- a/lib/optparse/date.rb
+++ b/lib/optparse/date.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 require 'date'
 
 OptionParser.accept(DateTime) do |s,|
diff --git a/lib/optparse/kwargs.rb b/lib/optparse/kwargs.rb
index ed58cc142b..59a2f61544 100644
--- a/lib/optparse/kwargs.rb
+++ b/lib/optparse/kwargs.rb
@@ -1,13 +1,23 @@
 # frozen_string_literal: true
-require 'optparse'
+require_relative '../optparse'
 
 class OptionParser
-  def define_by_keywords(options, meth, **opts)
-    meth.parameters.each do |type, name|
+  # :call-seq:
+  #   define_by_keywords(options, method, **params)
+  #
+  # :include: ../../doc/optparse/creates_option.rdoc
+  #
+  # Defines options which set in to _options_ for keyword parameters
+  # of _method_.
+  #
+  # Parameters for each keywords are given as elements of _params_.
+  #
+  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}", *opts[name]) do |o|
+        define("--#{name}=#{op}#{name.upcase}#{cl}", *params[name]) do |o|
           options[name] = o
         end
       end
diff --git a/lib/optparse/optparse.gemspec b/lib/optparse/optparse.gemspec
new file mode 100644
index 0000000000..885b0ec380
--- /dev/null
+++ b/lib/optparse/optparse.gemspec
@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+name = File.basename(__FILE__, ".gemspec")
+version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
+  break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
+Gem::Specification.new do |spec|
+  spec.name          = name
+  spec.version       = version
+  spec.authors       = ["Nobu Nakada"]
+  spec.email         = ["nobu@ruby-lang.org"]
+
+  spec.summary       = %q{OptionParser is a class for command-line option analysis.}
+  spec.description   = File.open(File.join(__dir__, "README.md")) do |readme|
+    readme.gets("") # heading
+    readme.gets("").chomp
+  end rescue spec.summary
+  spec.homepage      = "https://github.com/ruby/optparse"
+  spec.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
+  spec.licenses      = ["Ruby", "BSD-2-Clause"]
+
+  spec.metadata["homepage_uri"] = spec.homepage
+  spec.metadata["source_code_uri"] = spec.homepage
+
+  dir, gemspec = File.split(__FILE__)
+  excludes = %W[#{gemspec} rakelib test/ Gemfile Rakefile .git* .editor*].map {|n| ":^"+n}
+  spec.files = IO.popen(%w[git ls-files -z --] + excludes, chdir: dir, &:read).split("\x0")
+  spec.bindir        = "exe"
+  spec.executables   = []
+  spec.require_paths = ["lib"]
+end
diff --git a/lib/optparse/shellwords.rb b/lib/optparse/shellwords.rb
index bf31701b96..4feb1993d9 100644
--- a/lib/optparse/shellwords.rb
+++ b/lib/optparse/shellwords.rb
@@ -2,6 +2,6 @@
 # -*- ruby -*-
 
 require 'shellwords'
-require 'optparse'
+require_relative '../optparse'
 
 OptionParser.accept(Shellwords) {|s,| Shellwords.shellwords(s)}
diff --git a/lib/optparse/time.rb b/lib/optparse/time.rb
index ffc6ff000d..0ce651f6f6 100644
--- a/lib/optparse/time.rb
+++ b/lib/optparse/time.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: false
-require 'optparse'
+require_relative '../optparse'
 require 'time'
 
 OptionParser.accept(Time) do |s,|
diff --git a/lib/optparse/uri.rb b/lib/optparse/uri.rb
index 51550cf91b..31d10593b1 100644
--- a/lib/optparse/uri.rb
+++ b/lib/optparse/uri.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 # -*- ruby -*-
 
-require 'optparse'
+require_relative '../optparse'
 require 'uri'
 
 OptionParser.accept(URI) {|s,| URI.parse(s) if s}
diff --git a/lib/optparse/version.rb b/lib/optparse/version.rb
index b869d8fe51..b5ed695146 100644
--- a/lib/optparse/version.rb
+++ b/lib/optparse/version.rb
@@ -2,6 +2,11 @@
 # OptionParser internal utility
 
 class << OptionParser
+  #
+  # Shows version string in packages if Version is defined.
+  #
+  # +pkgs+:: package list
+  #
   def show_version(*pkgs)
     progname = ARGV.options.program_name
     result = false
@@ -47,6 +52,8 @@ class << OptionParser
     result
   end
 
+  # :stopdoc:
+
   def each_const(path, base = ::Object)
     path.split(/::|\//).inject(base) do |klass, name|
       raise NameError, path unless Module === klass
@@ -68,4 +75,6 @@ class << OptionParser
       end
     end
   end
+
+  # :startdoc:
 end