Question

I want to write a math vector template. I have a class which accepts type and size as template argument, with a lot of math operation methods.
Now I want to write specializations where Vector<3> for instance has x, y, z as members which refer to data[0..3] respectively.

The problem is that I don’t know how to create a specialization which inherits everything from the default template without creating either a base class or writing everything twice.

What’s the most efficient way to do this?

template<class Type, size_t Size>
class Vector {
    // stuff
};

template<class T>
class Vector<3,T>: public Vector {
    public:
        T &x, &y, &z;
        Vector(): Vector<>(), x(data[0]), y(data[1]), z(data[2]){}
        // and so on
};

Answer 1

Somehow you should be able to derive from default implementation, but you are specializing an instance, so how? it should be a non-specialized version that you can be able to derive from it. So that’s simple:

// Add one extra argument to keep non-specialized version!
template<class Type, size_t Size, bool Temp = true>
class Vector {
    // stuff
};
// And now our specialized version derive from non-specialized version!
template<class T>
class Vector<T, 3, true>: public Vector<T, 3, false> {
    public:
        T &x, &y, &z;
        Vector(): Vector<>(), x(data[0]), y(data[1]), z(data[2]){}
        // and so on
};