// Initializer list
#include <initializer_list>

template < int n >
class Vec
{
private:
    float e[n];
public:
    Vec(std::initializer_list<float> params);
    constexpr int GetSize( void ) const { return n; }
};

template < int n >
Vec<n>::Vec<n>(std::initializer_list<float> params) {
    static_assert(params.count() == n, “size mismatch”); // C++11
    std::initializer_list<float>::iterator it = params.begin();
    for (float &x: e) { // C++11 foreach
        x = *it;
        ++it;
    }
}