I have derived from std::tuple
and but was unable construct the derived class from an initializer list due to issues with class template argument deduction. Is there a better way to construct such a class beyond just giving it an already constructed tuple first{ std::tuple{1, 1.0f, 1u} };
.
template <typename T, typename... Types>
struct first : public std::tuple<T, Types...>
{
//using std::tuple<T, Types...>::tuple;
template<typename F>
requires std::invocable<F, T>
auto transform(F f)
{
auto result = *this;
std::get<0>(result) = f(std::get<0>(result));
return result;
}
};
int main()
{
//auto tuple = first{ 1, 1.0f, 1u };
auto tuple = first{ std::tuple{1, 1.0f, 1u} };
auto tuple2 = tuple.transform([](auto a) {return a + 3; });
}
Inherited constructors are not part of CTAD.
You might replicate std::tuple's CTAD:
template <typename T, typename... Types>
first(T, Types...) -> first<T, Types...>;
// auto tuple = first{1, 1.0f, 1u}; // is ok now
// auto tuple = first{ std::tuple{1, 1.0f, 1u} }; // broken now