I came up with some macros the other day trying to solve a kernel problem and I haven't seen them anywhere else and if I found one, I sure would have stolen it. :) I used this to have a single function-like macro service different numbers of parameters, essentially adding "optional parameter" support so I didn't have to have different version of the macro. IF_NONEMPTY(test, result) expands to result if test is non-empty, empty otherwise. IS_NONEMPTY(arg) expands to 0 if arg is empty, 0x1 if it isn't. OPT_OFFSETOF(type, member) isn't very useful in C++, but it is an example of how the above can be used. It expands to a compiler-time constant that is the offset of the member in the struct or union type, unless member isn't specified, in which case it's zero. #define __JUNK junk, #define _if_nonempty(arg1_or_junk, result) __if_nonempty(arg1_or_junk, result) #define __if_nonempty(__ignored, result, ...) result #define CONCAT_TOKEN(a, b) _concat_token(a, b) #define _concat_token(a, b) a ## b #define IF_NONEMPTY(test, result) _if_nonempty(__JUNK##test, result) #define IS_NONEMPTY(arg) CONCAT_TOKEN(0, IF_NONEMPTY(arg, x1)) #define OPT_OFFSETOF(type, m) ((size_t) &((*((type *)0)) IF_NONEMPTY(m,.)m))