Some notes about observables based on a blog entry

observable.rb

require 'observer'

class Source
  include Observable

  def ping(int)
    changed
    notify_observers(int)
  end
end

class Sink
  def update(int)
    puts int
  end
end

class SnarkySink
  def update(int)
    fail 'I aim to misbehave'
  end
end

source = Source.new
source.ping(3)

sink = Sink.new
source.add_observer(sink)
source.ping(7)

snarky_sink = SnarkySink.new
source.add_observer(snarky_sink)
source.ping(7)