how to return the last type of a variadic template?

问题

For example

template<typename... Ts>
LastTypeOfTs f();

How to return the last type of a variadic template?

回答1:

You could do a template recursion as below:

template<typename T, typename... Ts>
struct LastTypeOfTs {
   typedef typename LastTypeOfTs<Ts...>::type type;
};

template<typename T>
struct LastTypeOfTs<T> {
  typedef T type;
};

template<typename... Ts>
typename LastTypeOfTs<Ts...>::type f() {
  //...
}

LIVE DEMO

来源：https://stackoverflow.com/questions/26088683/how-to-return-the-last-type-of-a-variadic-template