get the size of `std::initializer_list` at compile time

Question

I am trying to implement the reshape function of fortran with C++(11/14) and I designed a function. This function accepts two std::initializer_list

Answer 1

Maybe its a bad idea to use std::initializer_list?

I think so. Consider

std::initializer_list<int> t;
std::initializer_list<int> a = {1,2,3};
std::initializer_list<int> b = {2,3};
if (rand() > 42)
    t = a;
else
    t = b;
auto reshaped_array = forreshape({1,2,3,4,5,6}, t);

In the above example, it's just impossible to know t.size() at compile time.

But you can ask the compiler to deduce the length of an initializer list by using a reference to C-style array, thanks to CWG 1591.

The definition of forreshape would look like:

template<int D, typename T>
auto forreshape(const std::initializer_list<T> & values, const int (&shape)[D])
{
    // use D...
}