illegal call to non-static member function

I am facig a problem..
this is the basic structure of my code.

#define @#problem() aaa::fn()

class aaa {
fn();
}

this is aaa.h

In xxx.cc

#include "aaa.h"
#include "xxx.h"

xxx::fn2() {

@#problem()

}

And xxx.h contains the instance of class aaa

when I try to compile it I get the error : illegal call to non static member function . See declaration of aaa::fn

re: illegal call to non-static member function

This is because you have tried to envoke aaa:fn() directly with instantiating an object of type aaa and the member function fn is not static so it can only be invoked through an instance of the class aaa.

re: illegal call to non-static member function

so class aaa {
fn();
} obj;

#define @#problem() obj.fn()

should that do???