> Any kind of repeating lists (enum + a switch over all the values, for example) are best handled by define-include-undefine sequences.

> See how it is done in LLVM, see all the .def files there. I cannot think of a single viable alternative to this method.

I've seen x-macros. I'm not sure I've seen them used to good effect, but I'd definitely be curious how the llvm code uses them.

> If you want a dense, readable, maintainable code - you're out of options, you have to resort to the preprocessor.

I guess it wasn't entirely obvious from my comment, but I wasn't arguing against using the preprocessor. It's self-contained, mostly usable with common tools, etc.. Anything that's supported on more than one platform or has compile time options generally depends on it. Dense, readable, maintainable code is definitely a good thing, which is one of the reasons I'd personally like to see a usable reflection land in C++.