Avoid Virtual Template - c++

Question

I'm having some trouble with C++: I have a class Primitive, it contains a member variable of an abstract buffer class..
Concrete buffer classes exist in many different forms for many different vertex types.. point-colour-normal, point-texcoord-normal, point-normal, point, etc.
I need to be able to add any type of vertex to a buffer held by classes that derive from primitive, for example quadsets, tri-lists, etc.
class Buffer {
//...
template<class T>
virtual void Add(const T&) = 0; // nope! Not compilable
virtual void Add(boost::any&) = 0; // I have been told no boost allowed either..
}
template<class T>
TypedBuffer : public Buffer {
//..
public:
std::vector<T> buffer;
public:
virtual void Add( const T& elem ) { buffer.push_back( elem ); }
}
class Primitive {
protected:
Buffer vertices;
public:
// How can I allow this to happen? \/
virtual void AddVert( const vec3& v) { vertices.Add( v ); }
}
class QuadSet : public Primitive { /*QuadSet Specifics..*/ }
void main(){
QuadSet q;
q.Add( COLOURED_VERT(vec3(1, 2, 3), vec3(0.5,0.5,0.5) ) );
}
Please Help!

Answer 1

When facing a similar problem, I ended up using type eraser. However in my example it requires to use something like reinterpret_cast:
class Buffer {
virtual void Add(const void*) = 0;
};
template <typename T>
class TypedBuffer: Buffer {
virtual void Add(const void* e) { buffer.push_back(*static_cast<T*>(e)); }
};
class Primitive {
virtual void AddVert(const vec3& v) { vertices.Add(reinterpret_cast<const void*>(&v)); }
};