An extension to the subtype relationship in C++ implemented with template metaprogramming

Families of independent classes, where each class represents a separate, orthogonal concern are highly attractive for implementing collaboration-based design. However, required subtype relationship between such families cannot be expressed in many programming languages. This paper presents a framework to handle collaborating groups of classes using template metaprogramming based on standard C++ features in the style of Loki::Typelist. Our solution provides tailor-made implicit conversion rules between appropriate groups, inclusion polymorphism and a tool for dynamic binding.