What concept is being exhibited in this macro wrapping?

Question

A bunch of code just got handed over to me and I got baffled by macros in the header. I could not understand what they are for:

#define WRAPPER_MACRO(symbol) sym         


        

Answer 1

As @Michael said, we'll need to see the real macros to know for sure. But without them, I'm willing to take a few guesses that might help you out.

The macro nesting is probably a stringification thing. This bit of code is from a codebase I maintain:

// As per http://gcc.gnu.org/onlinedocs/cpp/Stringification.html:
// "If you want to stringify the result of expansion of a macro argument, you
// have to use two levels of macros."
#ifndef STRINGIFY
#define STRINGIFY(s) TOSTRING(s)
#define TOSTRING(s) #s
#endif

I'm also guessing your PREFIXED_ANOTHER_SYMBOL macro is doing something similar to this, using the # or ## preprocessor directives to prepend a certain symbol to whatever you feed the macro.