Is there a way to enforce full initialization of std::array

Question

I am using std::array (N is a fixed template-variable).

#include
template
struct A{
   size_t fun         


        

Answer 1

You can enforce this by using parameter pack, but with a bit different syntax:

#include 

template
struct A{
   template
   size_t function(T&&... nums)
   {
     static_assert(sizeof...(nums) == N, "Wrong number of arguments");
     std::array arr = { std::forward(nums)... };
     return arr[N-1];
   }
};

int main(){
   A<5> a;
   a.function(1,2,3,4,5); // OK
   a.function(1,2,4,5);   // Compile-time error
}

But, I think there is no good way to enforce that in compile time. I would just use assert(il.size() == N) in production code to check size of initializer list.