Transforming a Variant

14 May 2020

Q: How do I transform a variant<X, Y, Z> V into variant<vector<X>, vector<Y>, vector<Z>>?

A: Use mp_transform<std::vector, V>.

Q: And what if I want to use my own allocator A, that is, want variant<vector<X, A>, vector<Y, A>, vector<Z, A>>?

A: Use mp_transform_q<mp_bind_back<std::vector, A>, V>.

Q: But my allocator is a template. How about variant<vector<X, A<X>>, vector<Y, A<Y>>, vector<Z, A<Z>>>?

A: Use mp_transform<std::vector, V, mp_transform<A, V>>.

Q: Does Mp11 answer every question with a cryptic one liner?

A: Yes.