Re: [boost] Nasty compile time reflection and iteration for POD types using C++14 without macro

Antony Polukhin writes:

Hello,

I've come up with a trick that may be useful in Boost.Hana, Boost.Serialization or some other libraries.

Definitely an interesting and novel trick. Although, as you said, it is a nasty trick, and such things would be better if supported in the language (IMO). Until then, this trick might be useful.

[...] * there's no known to me way to make get<>() method constexpr

If we computed the offset at which the n-th member lies inside the struct, couldn't we use something like template decltype(auto) get(const T& val) noexcept { std::size_t offsets[] = {}; // assume this is known using U = std::tuple_element_t; return *static_cast( // <-- is this UB? static_cast(std::addressof(val)) + offsets[I] ); } Because if that works, computing the offsets is feasible.