How to make a protected singleton method

Question

How can I make the following method some_protected protected or private? It should be implemented without inheritance.

module Sample
  def self.some_public
    some_protected
  end

  protected

  def self.some_protected
    puts 'Bingo!'
  end
end

Sample::some_public     # Bingo!
Sample::some_protected  # Bingo! (but expected an error that method is not accessible)

Answer 1

Working within the singleton class is probably the easiest.

module Sample; end

class <<Sample
  def some_public
    some_protected
  end
  protected def some_protected
    puts 'Bingo!'
  end
end