惱人的動態字串

example.rb

  def tcat_delivery_list
    @tcat_delivery_list or begin
      delivery_option = DeliveryOption.valid.find_by(owner_type: 'Merchant', owner_id: merchant.id, region_type: 'tw_tcat')
      return @tcat_delivery_list = TcatDeliveryList.new('tw_tcat', nil) if delivery_option.blank?
      contract_code = delivery_option.config_data['contract_code'].tap { |code| raise "DeliveryOption #{delivery_option.id} has no contract_code" if code.blank? }
      @tcat_delivery_list = TcatDeliveryList.new('tw_tcat', contract_code)
    end
  end

  def tcat_pay_delivery_list
    @tcat_pay_delivery_list or begin
      delivery_option = DeliveryOption.valid.find_by(owner_type: 'Merchant', owner_id: merchant.id, region_type: 'tw_tcat_pay')
      return @tcat_pay_delivery_list = TcatDeliveryList.new('tw_tcat_pay', nil) if delivery_option.blank?
      contract_code = delivery_option.config_data['contract_code'].tap { |code| raise "DeliveryOption #{delivery_option.id} has no contract_code" if code.blank? }
      @tcat_pay_delivery_list = TcatDeliveryList.new('tw_tcat_pay', contract_code)
    end
  end

  %w(tcat tcat_pay).each do |type|
    class_eval <<-RUBY, __FILE__, __LINE__ + 1
      def #{type}_delivery_list
        @#{type}_delivery_list or begin
          region_type = "tw_%s" % :#{type}.to_s
          delivery_option = DeliveryOption.valid.find_by(owner_type: 'Merchant', owner_id: merchant.id, region_type: region_type)
          return @#{type}_delivery_list = TcatDeliveryList.new(region_type, nil) if delivery_option.blank?
          contract_code = delivery_option.config_data['contract_code'].tap { |code| raise "DeliveryOption %s has no contract_code" % delivery_option.id if code.blank? }
          @#{type}_delivery_list = TcatDeliveryList.new(region_type, contract_code)
        end
      end
    RUBY
  end