secrecy.rb

module SecretKey
  protected

  def fix_plumbing(*args)
    _fix_plumbing(*args) if defined?(:_fix_plumbing)
  end

  def twist_knob
    _twist_knob if defined?(:_twist_knob)
  end
end

class Matt
  include SecretKey

  private
  
  def _fix_plumbing(house)
    house.twist_knob
  end
end

class House
  include SecretKey

  private

  def _twist_knob
    puts "squeak squeak"
  end
end

class Jessica
  include SecretKey

  def ask_for_repair(plumber, house)
    plumber.fix_plumbing(house)
  end
end

class Sam
  def fix_plumbing(house)
    house.twist_knob
  end

  def ask_for_repair(plumber, house)
    plumber.fix_plumbing(house)
  end
end

jessica = Jessica.new
matt = Matt.new

jessica.ask_for_repair(matt, House.new)

# Sam isn't allowed in on the secret
sam = Sam.new
sam.fix_plumbing(House.new)

sam.ask_for_repair(matt, House.new)

I feel excluded. 😢