iterating over variadic template's type parameters

Question

I have a function template like this:

template 
do_something()
{
  // i\'d like to do something to each A::var, where var has static storag         


        

Answer 1

As an example, suppose you want to display each A::var. I see three ways to acomplish this as the code below illustrates.

Regarding option 2, notice that the order in which the elements are processed is not specified by the standard.

#include 
#include 

template 
struct Int {
    static const int var = i;
};

template 
void do_something(std::initializer_list list) {
    for (auto i : list)
        std::cout << i << std::endl;
}

template 
void expand(A&&...) {
}

template 
void do_something() {

    // 1st option:
    do_something({ A::var... });

    // 2nd option:
    expand((std::cout << A::var << std::endl)...);

    // 3rd option:
    {
        int x[] = { (std::cout << A::var << std::endl, 0)... };
        (void) x;
    }
}

int main() {
    do_something, Int<2>, Int<3>>();
}