BCDice v3でevalの戻り値を結果用インスタンスにする案

game_system.rb

require_relative "rands"
require_relative "result"

module BCDice
  class Evaluator
    class << self
      def eval(command)
        new(command).eval
      end
    end

    def initialize(command)
      @command = command
    end

    def eval(randomizer: Randomizer.new)
      @command = Preprocessor.process(@command, self, randomizer)

      result = AddDice.eval(self, randomizer) || eval_game_system_specific_command(randomizer)
      return nil unless result

      result.rands = randomizer.rands
      result
    end

    private

    def eval_game_system_specific_command(randomizer); end
  end

  module GameSystem
    class Cthulhu < Evaluator
      def eval_game_system_specific_command(randomizer)
        m = /^CC<=(\d+)$/.match(@command)
        return nil unless m

        target_number = m[1].to_i
        result = Result.new

        dice = randomizer.roll_once(100)
        result.condition = dice <= target_number

        sequence = [
          "(#{@command})",
          dice,
          result.success? ? "成功" : "失敗"
        ]

        result.text = sequence.join(" ＞ ")

        result
      end
    end
  end
end

randomizer.rb

module BCDice
  class Randomizer
    attr_reader :rands

    def initialize
      @rands = []
    end

    def roll_once(sides)
      value = Kernel.rand(sides) + 1
      @rands.push(value)

      value
    end
  end
end

result.rb

class Result
  def initialize
    @secret = false
    @success = false
    @failure = false
    @critical = false
    @fumble = false
  end

  attr_accessor :text, :rands
  attr_writer :success, :failure, :critical, :fumble

  def secret?; @secret end
  def success?; @success end
  def failure?; @failure end
  def critical?; @critical end
  def fumble?; @fumble end

  def condition=(condition)
    @success = condition
    @failure = !condition
  end
end