What would be a set of nifty preprocessor hacks (ANSI C89/ISO C90 compatible) which enable some kind of ugly (but usable) object-orientation in C? I am familiar with a few different object-oriented languages, so please don't respond with answers like "Learn C++!". I have read "Object-Oriented Programming With ANSI C" (beware: PDF format) and several other interesting solutions, but I'm mostly inte