Extending a Ruby module in another module, including the module methods

Question

Whenever I try to extend a ruby module, I lose the module methods. Neither include nor extend will do this. Consider the snippet:

module A 
  def self.say_         


        

Answer 1

I don't like everyone using self.included. I have simpler solution:

module A
  module ClassMethods
    def a
      'a1'
    end
  end
  def a
    'a2'
  end
end

module B
  include A

  module ClassMethods
    include A::ClassMethods
    def b
      'b1'
    end
  end
  def b
    'b2'
  end
end

class C
  include B
  extend B::ClassMethods
end

class D < C; end

puts D.a
puts D.b
puts D.new.a
puts D.new.b