Most important things about C++ templates… lesson learned

Question

What are most important things you know about templates: hidden features, common mistakes, best and most useful practices, tips...common mistakes/oversight/assumptions

Answer 1

I'd have to say Coplien's Curiously Recurring Template Pattern (CRTP) is the one template trick that I find myself reaching for over & over again. Essentially it allows you to inject statically customized functionality into a derived class by inheriting from a base class that is parameterized on the derived class name. Mind boggling, but amazingly useful (some call it static polymorphism).

Also, I'll second Neil Butterworth's advice to read "C++ Templates" and throw in Alexandrescu's Modern C++ Design.