I need trait to check if serialization is possible using cereal. I've already used
cereal::traits::is_output_serializable<T, cereal::BinaryOutputArchive>
cereal::traits::detail::count_output_serializers<T, cereal::BinaryOutputArchive>
(plus the symmetric version for input serialization).
Putting such checks in if constexpr passes (evaluates to true even though my type is not serializable) but later on it breaks within cereal saying that the very same trait failed(!) I'm using T=cv::Mat.
I wrote my own based on some static asserts I found in Cereal. I have a base case with a bunch of specialisations I need for my own code. The specialisations are needed as the base case is true for std::shared_ptr<T> even if T isn't itself serialisable.
/// Meta programming constant, can you serialise the type T to the Cereal archive ARCHIVE?
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealOutputArchiver
= not std::is_pointer<T>::value and cereal::traits::detail::count_output_serializers<T, ARCHIVE>::value != 0;
// specialisation for vectors
template<typename ARCHIVE, typename T, typename A>
static constexpr bool kHasCerealOutputArchiver<ARCHIVE, std::vector<T, A>> = kHasCerealOutputArchiver<ARCHIVE, T>;
// specialisation for shared_ptrs
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealOutputArchiver<ARCHIVE, std::shared_ptr<T>> = kHasCerealOutputArchiver<ARCHIVE, T>;
// specialisation for shared_ptrs to const
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealOutputArchiver<ARCHIVE, std::shared_ptr<const T>> = kHasCerealOutputArchiver<ARCHIVE, T>;
/// Meta programming constant, can you serialise the type T from the Cereal archive ARCHIVE?
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealInputArchiver
= not std::is_pointer<T>::value and cereal::traits::detail::count_input_serializers<T, ARCHIVE>::value != 0;
// specialisation for vectors
template<typename ARCHIVE, typename T, typename A>
static constexpr bool kHasCerealInputArchiver<ARCHIVE, std::vector<T, A>> = kHasCerealInputArchiver<ARCHIVE, T>;
// specialisation for shared_ptrs
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealInputArchiver<ARCHIVE, std::shared_ptr<T>> = kHasCerealInputArchiver<ARCHIVE, T>;
// specialisation for shared_ptrs to const
template<typename ARCHIVE, typename T>
static constexpr bool kHasCerealInputArchiver<ARCHIVE, std::shared_ptr<const T>> = kHasCerealInputArchiver<ARCHIVE, T>;