null_object_fix.rb

class Config
  def self.emailer
    if email_disabled? then NullMailer else
      if has_amiko? then AmikoAdapter else MailerMonkey end
    end
  end
end
class NullMailer
  def initialize ; end
  def send_email ; true ; end
end
def advertise_discount_for_movie
  moviegoers = Moviegoer.interested_in(params[:movie_id])
  EmailList.new(Config.emailer).send_email_to(moviegoers)
  end
end