Templates generate multiple classes and multiple functions, so any template code not dependent on a template parameter (either non-type template parameters or type parameters) causes bloat: eliminate bloat due to non-type template parameters by replacing template parameters with function parameters or class data members; reduce bloat caused from type parameters by sharing implementations for instantiation types with identical binary representations.

In derived class templates, refer to names in base class templates via a this-> prefix, via using declarations, or via an explicit base class qualification.

When declaring template parameters, both class and typename are interchangeable. When identifying nested dependent type names, use typename, except in base class lists or as a base class identifier in a member initialization list.

Classes support explicit interfaces based on function signatures, as well as runtime polymorphism through virtual functions; templates support implicit interfaces based on valid expressions, as well as compile-time polymorphism through template instantiation and function overloading resolution.

Being more complex than single inheritance, Multiple inheritance (MI) can lead to ambiguity issues and to the need for virtual inheritance, the latter of which imposes costs in size, speed, and complexity of initialization and assignment, so it’s more practical to make “empty” virtual base classes.