Macro taking input from surrounding context

I know this is probably a bit of a stretch to ask, but I was wondering if there was any way to do this nicely:

I have a function map:

std::map<std::string, std::function<int(int)> > fnmap;

And a bunch of functions that I'd lik开发者_Python百科e to add to this map.

Is there any way to decorate the functions so that I can just have:

MAPNAME("FN") int fn(int param) {}

MAPNAME("FN2") int fn2(int param2) {} ..

which should result in fnmap["FN"] = &fn;

As I said above, this is a bit of a stretch, but, I figured worth asking!

---

struct Remember {
    static std::map<std::string, std::function<int(int)> > map;
    Remember (int (*f) (int), const char * name) {
        map [name] = f;
    }
};

// Needs anonymous namespace to be able to include it more than once in a header.
#define MAPNAME(x) namespace {Remember _##__LINE__ (x, #x);}

int f1 (int);
int f2 (int);
MAPNAME (f1)
MAPNAME (f2)

The functions need to be declared before you invoke MAPNAME, so it doesn't really count as decoration.

Macros don't understand C styntax, so they can't pull in any "context" which you haven't given them.