[attractivechaos]

For linked lists and binary trees, intrusive data structures are better.

> Well, except the first one, template macros, where I can’t really find any pro, only cons.

For toy examples, the first (expanding a huge macro) has mostly cons. But it is more flexible when you want to instantiate different parts of the header. The second approach can work but will be clumsy in this case because the whole header is considered as one unit.