Ruby private vs protected

hats.rb

class Hat

  def explain
    puts "You have a #{hat_type} hat!"
  end

  private

  def hat_type
    raise 'Child must implement hat type'
  end

  def default_hat_type
    "Default"
  end

  protected

  def secret_hat
    "default secret"
  end
end

class BigHat < Hat

  def hat_type
    "BIG"
  end
end

class SmallHat < Hat
  def explain
    puts "You have a #{default_hat_type} hat!"
  end

  def secret_hat(other_hat)
    puts "Secret hat is #{other_hat.secret_hat}"
  end
end

class NotHat
  def can_see_hat?(hat)
    puts "Hat secret: #{hat.secret_hat}"
  end
end

h = SmallHat.new
h_big = BigHat.new
no_hat = NotHat.new

h.secret_hat(h_big)

no_hat.can_see_hat?(h_big) # breaks, no_hat is not a hat