Wie mir die Lösung von AH besser gefällt

ccc_kata.rb

require 'socket'

class CalcMessage
  @@operators = {
   'ADD' => :+,
   'MULTIPLY' => :*,
   'SUBTRACT' => :- }

  def initialize request
    @command, @id, *@numbers = request.split ':'
  end

  def exit?
    @command == '__SHUTDOWN__'
  end

  def numbers
    @numbers.map &:to_i
  end

  def operator
    @@operators[@command]
  end

  def answer
    "#{@id}:#{numbers.inject &operator}"
  end
end

class UDPConversation
  @@max_message_size = 4097

  def initialize args
    @answer_host, @answer_port = args[:answer_to].split ":"

    listen_host, listen_port = args[:listen_on].split ":"
    @receiver = UDPSocket.new
    @receiver.bind listen_host, listen_port
  end

  def request
    @receiver.recvfrom(@@max_message_size)[0]
  end

  def respond data
    UDPSocket.new.send data, 0, @answer_host, @answer_port
  end

  def endless args
    loop { respond yield request }
  end

  def self.endless args, &block
    UDPConversation.new(args).endless args, &block
  end
end

UDPConversation.endless(:listen_on => "0.0.0.0:9000",
                        :answer_to => "localhost:9001") do |request|
  message = CalcMessage.new request
  exit if message.exit?
  message.answer
end