Simple message passing example in Ruby (1)

MessagePassing1.rb

class Repeater
   @@subscribers = []
   
   # Add the new subscriber to our list of subscribers
   def subscribe(newSubscriber)
      @@subscribers << newSubscriber
   end
   
   # Send the message to all of our subscribers
   def broadcast(message)
      @@subscribers.each { |subscriber| subscriber.accept(message) }
   end
end

module Subscriber
   # This will alert of us if we include subscriber
   # but don't implement all of its methods
   def accept(message)
      raise "not implemented"
   end
end

# Our first subscriber, Sub1
class Sub1
   include Subscriber

   def initialize(repeater)
      @repeater = repeater
      @repeater.subscribe(self)
   end
   
   # Simply print out the message on accepting
   def accept(message)
      puts "#{self.class} accepted #{message}"
   end
   
   # A method to allow us to send messages to the repeater
   def send(message)
      @repeater.broadcast(message)
   end
end

#Our second subscriber, Sub2
class Sub2
   include Subscriber

   def initialize(repeater)
      @repeater = repeater
      @repeater.subscribe(self)
   end
      
   def accept(message)
      puts "#{self.class} accepted #{message}"
   end
end

r = Repeater.new
sub1 = Sub1.new(r)
# Send a message when Sub1 is the only subscriber
sub1.send("Hello World!")
sub2 = Sub2.new(r)
# Send a message when Sub2 has been added to the subscriber list
sub1.send("Hi, new guy!")