super_method

class A
  def show
    "a method"
  end
end

class B<A
  def show
    "b method"
  end
end

B.new.method(:show).super_memthod.call  #ruby 2.2可用

class A
  def show
    "a method"
  end
end

class B<A
  alias_method :super_show ,:show
  def show
    "b method"
  end
end
B.new.super_show