Digest::***をキーワード引数とかで呼び出せるようにしたラッパーモジュール

hashsum

#!/usr/bin/env ruby

require 'tmpdir'
require 'open-uri'
require 'digest'
require 'pathname'

module HashSum
  def self.define_component(name)
    define_method(name) do |file: nil, url: nil, str:nil|
      case
      when file
        return eval("Digest::#{name}.file(File.expand_path(file)).to_s")
      when url
        Dir.mktmpdir do |tmpdir|
          download_path = Pathname(tmpdir) + File.basename(url)
          open(download_path, 'wb') do |file|
            open(url) {|data| file.write(data.read) }
          end
          return eval("Digest::#{name}.file(download_path).to_s")
        end
      when str
        return eval("Digest::#{name}.hexdigest(str)")
      end
    end
  end

  def method_missing(name, *args)
      eval("Digest::Base >= Digest::#{name}")
    rescue LoadError, NoMethodError, SyntaxError
      super
    else
      define_component(name)
      send(name, args[0])
  end

  def respond_to?(method)
      eval("Digest::Base >= Digest::#{method}")
    rescue LoadError, NoMethodError, SyntaxError
      super
    else
      true
  end

  extend self
end

if __FILE__ == $PROGRAM_NAME
  require 'optparse'

  options = {}
  OptionParser.new do |opt|
    HashSum.tap {|o| o.send(:define_component, :SHA256) }.method(:SHA256).parameters.flatten.reject {|v| v.eql?(:key) }.each do |args|
      opt.on("--#{args.to_s}=VALUE") {|v| options[args] = v }
    end
    opt.on("--type=VALUE") {|v| options[:type] = v.upcase }
    opt.parse!(ARGV)
  end

  if options.reject {|k, _| k.eql?(:type) }.values.all?(&:nil?)
    STDERR.puts "#{File.basename(__FILE__)}: require option\nTry --help for help"
    exit 1
  end

  puts HashSum.send(options[:type] || :SHA256, options.reject {|k, v| k.eql?(:type) || v.nil? })
end