C++ CRTP and accessing derived's nested typedefs from base

Question

edit: I\'ll put a github link here when I am done altering my design for anyone who is interested.

Background

I\'m replacing a

Answer 1

There's no need for the traits class. You can just use type_key directly in base.

You cannot, however, avoid passing the type explicitly to base. At the time base is instantiated, the typedef in derived has not yet been seen by the compiler (more exactly: the class derived is not yet complete — how could it, given that even its base class doesn't exist yet).