FizzBuzz Quiz https://qiita.com/sumim/items/f26902f2b813c075a619

fizz_buzz.rb

class X < BasicObject
  MAP = {
    fizz: 3,
    buzz: 5
  }

  def initialize(n)
    @n = n
    @result = nil
  end

  MAP.each do |name, x|
    define_method name do
      if @n.modulo(x).zero?
        @result ||= ''
        @result << name.to_s.capitalize
      end

      self
    end
  end

  private

  def method_missing(*args)
    result.__send__(*args)
  end

  def result
    @result || @n
  end
end

using Module.new {
  refine Integer do
    X::MAP.each_key do |k|
      define_method k do
        X.new(self).__send__(k)
      end
    end
  end
}

p 1.fizz #=> 1
p 3.fizz #=> "Fizz"
p 1.buzz #=> 1
p 5.buzz #=> "Buzz"
p 1.fizz.buzz #=> 1
p 3.fizz.buzz #=> "Fizz"
p 5.fizz.buzz #=> "Buzz"
p 15.fizz.buzz #=> "FizzBuzz"
p 15.buzz.fizz #=> "BuzzFizz"