I left out the overload stuff on purpose. I didn't want to get into it because it's just one way of doing things, and the recipe is not a concept. If someone gets the idea, they can implement the other stuff so it fits into how the rest of the system does things. I'd much rather see people use a consistent metaphor rather than cobble together different styles.

The Gang of Four, or any other designs pattern book, is not a cookbook ;)