C++ (Qt)class A{ const int dsize; double d[dsize]; A():dsize(3) { } };
C++ (Qt)class A{ static const int dsize = 3; double d[dsize]; A() { }};
template <class Type, size_t N>class A{.. Type d[N];...};
typedef A<double, 4> Quad; typedef A<double, 3> Triangle;
C++ (Qt)using Quad = std::array<double, 4>; using Triangle = std::array<double, 3>;