"events": very similar to Observable, but cleaner, IMO. events are listened to and sent in instance space, but registered in class space. example:

class C

  include EventSource
  event :goat, :boat

  def send_events
    send_event :goat
    send_event(:boat, 3)
  end

end

c = C.new c.on_event(:goat) { puts "got goat!" } c.on_event(:boat) { |x| puts "got boat: #{x}" }

Defining them in class space is not really necessary, except as an error-checking mechanism.