Hands-On Design Patterns with C++

CRTP as a delegation pattern

So far, we have used CRTP as a compile-time equivalent of dynamic polymorphism, including virtual-like calls through the base pointer (compile-time, of course, with a template function). This is not the only way CRTP can be used. In fact, more often than not, the function is called directly on the derived class. This is a very fundamental difference—typically, public inheritance expresses the is-a relationship—the derived object is a kind of a base object. The interface and the generic code are in the base class, while the derived class overrides the specific implementation. This relation continues to hold when a CRTP object is accessed through the base class pointer or reference. Such use of CRTP is sometimes ...