How to set std::array size via parameter pack arguments?

Question

I have an N-dimensional Matrix class that has a constructor with a parameter pack. Is it possible to set the size of the std::array member variable depending on the values in the parameter pack? As far as I understand the values in the parameter pack should be known at compile time.

template<size_t N>
class Matrix {
public:
    template<typename... Exts>
    Matrix(Exts... exts) : dimSizes{exts...} { }

private:
    std::array<size_t, N> dimSizes;
    std::array<float, N> data;
    // e.g something like this: std::array<float, dimSizes[0]> data;
};

int main(void) {
    Matrix<3> mat(2, 3, 2);
    return 0;
}

Answer 1

Is it possible to set the size of the std::array member variable depending on the values in the parameter pack?

// e.g something like this: std::array<float, dimSizes[0]> data;

No, as far I know is impossible exactly as you want.

Because, this way, different instances of the same class would contain members with same name but different types. Strictly forbidden in a strongly typed language as C++.

If you want a std::array with different size, you have to differentiate the types; so the dimension for the second std::array has to be a template parameter.

Obviously you can substitute the std::array with a container that doesn't depend from the size; as suggested by Piotr Skotnicki a possible solution is std::vector