#define 매크로의 사용 문법을 알고 싶습니다.

#define Z x->y->z
int foo(struct A* a)
{
    return a->Z->function(a->Z);
}
#undef Z

#define ___ERROR_ENTRY___(_x_) case _x_: return "[" #_x_ "]"
const char* errno2str(const int error_no)
{
	switch (error_no) {
	___ERROR_ENTRY___(E2BIG);
	___ERROR_ENTRY___(EACCES);
	___ERROR_ENTRY___(EADDRINUSE);
	___ERROR_ENTRY___(EADDRNOTAVAIL);
	___ERROR_ENTRY___(EAFNOSUPPORT);
	___ERROR_ENTRY___(EAGAIN);
	___ERROR_ENTRY___(EALREADY);
	___ERROR_ENTRY___(EBADF);
	...
	}
	return "[!E_NOTPOSIX]";
}

template<int errno_>
class Error {
public:
	const char* c_str() const { return "!E_NOTPOSIX"; }
};
 
#define DECL_ERROR( _x_ ) template<>\
	class Error<_x_> {\
	public:\
		const char* c_str() const { return #_x_; }\
	}; Error<_x_> Instance_##_x_;
 
 
DECL_ERROR(E2BIG);
DECL_ERROR(EACCES);
DECL_ERROR(EADDRINUSE);
DECL_ERROR(EADDRNOTAVAIL);
DECL_ERROR(EAFNOSUPPORT);
DECL_ERROR(EAGAIN);
DECL_ERROR(EALREADY);
DECL_ERROR(EBADF);