T8 v8) : v1_(v1), v2_(v2), v3_(v3), v4_(v4), v5_(v5), v6_(v6), v7_(v7),
      v8_(v8) {}

  template <typename T>
  operator ParamGenerator<T>() const {
    const T array[] = {static_cast<T>(v1_), static_cast<T>(v2_),
        static_cast<T>(v3_), static_cast<T>(v4_), static_cast<T>(v5_),
        static_cast<T>(v6_), static_cast<T>(v7_), static_cast<T>(v8_)};
    return ValuesIn(array);
  }

 private: