Restrict variadic template arguments

Question

Can we restrict variadic template arguments to a certain type? I.e., achieve something like this (not real C++ of course):

struct X {};

auto foo(X... args)
         


        

Answer 1

How about static_assert and helper template method (c++11 solution):

template 
int assert_impl() {
   static_assert(b, "not convertable");
   return 0;
}

template 
void foo_x(Args... args) {
    int arr[] {assert_impl::value>()...};
    (void)arr;
}

One more c++11 this one uses "one-liner" sfinae-based solution:

template {typename std::enable_if::value, int>::type{}...})>
void foo_x(Args... args) {
}