There are two well known macros from the preprocessor which every macro-sorcer must know. They are __FILE__ and __LINE__. You probably already know about them but anyway, __FILE__ will give you the current file and __LINE__ the current line. Easy, huh?
int main() {
printf("%s : %i", FILE, LINE);
return 0;
}
The program above would give you "main.cpp : 3" as a result. There is nothing going on at execution time, it's all preprocesor wizardy. In fact with "g{++/cc} -E" you can even check what the "real" output is (-E means to return the preprocessor output. Keep in mind a lot of stuff will be included from the headers you use).
int main() {
printf("%s : %i", "main.cpp", 3);
return 0;
}
Well that's nice and all, but g++ can top this easily:
int main() {
std::cout << PRETTY_FUNCTION << "n";
return 0;
}
There are a couple of notable things about this new "pretty function" thing: * 1. It will demangle a function's name * 2. This time it isn't a preprocessor secret thing but a real variable g++ will create.
You can easily use this for better logging functions now (with some macro wizardy, obviously).
In reply to this post, Nicolás Brailovsky » Blog Archive » Cool C++0X features VI: A variadic wrapper commented @ 2011-05-17T09:06:06.000+02:00:
[...] you want to wrap do_something with something else (Remember __PRETTY_FUNCTION__?). This is a solution, the worst one [...]
Original published here.