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

This question is a bit like "I'm going to implement most of my library using functions, what are the common mistakes in using functions?" It's hard to come up with sensible answers to such questions, but here's my advice - read a good book. I recommend "C++ Templates" by Vandevoorde & Josuttis,