simple_pubsub.rb

module PubSub
  class << self
    def create type, channel, object
      channel = channel.to_sym

      case type
      when :listener
        listeners[channel] ||= Array.new
        listeners[channel] << object
        channels[channel] ||= Array.new
        Listener.new object, channel
      when :emitter
        emitters[channel] ||= Array.new
        emitters[channel] << object
        channels[channel] ||= Array.new
        Emitter.new object, channel
      else
        raise ArgumentError, 'Unrecognized type.'
      end
    end

    def listeners
      @listeners ||= Hash.new
    end

    def emitters
      @emitters ||= Hash.new
    end

    def channels
      @channels ||= Hash.new
    end
  end

  class Emitter
    def initialize object, channel
      @object = object
      @channel = PubSub.channels[channel]
    end

    def emit message
      @channel << message
    end
  end

  class Listener
    def initialize object, channel
      @object = object
      @channel = PubSub.channels[channel]
      @cursor = -1
    end

    def get
      if @channel.length > (@cursor + 1) then
        @cursor += 1
        @channel[@cursor]
      else
        raise NoData, "No data in channel: `#{@channel}'."
      end
    end
  end

  class NoData < RuntimeError; end
end

class Reciever
  def initialize name = nil
    @pubsub = PubSub.create :listener, :channel_1, self
    @name = name || object_id
  end
  attr :pubsub

  def listen
    loop do
      begin
        message = pubsub.get
        print "< #{Time.now.to_i} @ R##{@name} : #{message} >\n"
        break if message == :end
      rescue PubSub::NoData
        sleep 0.05
        retry
      end
    end
  end
end

class Sender
  def initialize name = nil, stuff = nil
    @pubsub = PubSub.create :emitter, :channel_1, self
    @stuff =  stuff || [1, 2, 3, 'a', 'b', 'c']
    @name = name || object_id
  end
  attr :pubsub

  def send_stuff
    until @stuff.empty? do
      pubsub.emit @stuff.shift
    end
  end
end

require 'thread'
require 'pry'

t1 = Thread.new do
  Reciever.new('Sally').listen
end

t2 = Thread.new do
  Reciever.new('Sue').listen
end

t3 = Thread.new do
  Sender.new('Bob', [:x, :y, :z, :end]).send_stuff
end

Sender.new('Billy').send_stuff

t3.join
t1.join
t2.join

binding.pry