Implementing C++03 Tuple was awful / hilarious. I wrote the tuple implementation which was included in g++ for a while (technically libstdc++) -- it used some

Implementing C++03 Tuple was awful / hilarious. I wrote the tuple implementation which was included in g++ for a while (technically libstdc++) -- it used some reasonably awful preprocessor to generate the different arities of tuple. Once you get to C++11, you at least didn't need to do it with pre-processor magic.