Question

Consider the following pseudo code :

template<class... T>
struct worker : unique<T...>::type...{};
struct x{};
struct y{};
struct z{};

Is it possible to write a template unique such that it generates a parameter pack consisting of only unique types among Ts, so that worker<x,y,x,z> will be directly derived from x, y, z respectively ,in that order, given Ts are non final classes?

Answer 1

AFAIK: No.

The problem is that type is the result of a typedef directive, and typedef cannot alias packs. It is actually a bother, and most often computations on packs require introducing a wrapper type (such as template <typename...> struct pack {};) just to be able to pass them around.