class A
  def say
    puts "A"
  end
end

module B
  def self.role(klass, &block)
    ref = refine(klass) { }
    ref.module_eval(&block)
  end

  role A do
    def say
      puts "B"
    end
  end
end

class C
  using B

  def say
    A.new.say
  end
end

A.new.say # => A
C.new.say # => B