Alternative usages to `type_t` which might be added in the doc

[Jarod42]

type_t might also be used to force specific type in variadic case:

template <typename ... Ts>
struct Example
{
#if 0
   // "Alternative" ways:

   // No type checks (and might be problematic with copy constructor)
    template <typename ... Us> Example(Us&&...);

    // SFINAE way
    // Allows indeed to pass initial types, but verbose
    // and condition might be non trivial
    template <typename ... Us,
                     std::enable_if_t<(std::is_constructible<std::string, Us>&& ...), int> = 0>
    Example(Us&&...);

#else
    // Bonus: non template, so we might use {} is the call:
    // Example<int, int>("next is empty", {})
    Example(type_t<const std::string&, Ts>... args) : names{args...} {}
#endif
    std::array<std::string, sizeof...(Ts)> names;
};

or (with also index_constant)

template <std::size_t ... Is>
void Example2(std::index_sequence<Is...>, type_t<float, index_constant<Is>>...);