Question

I have thousands of function wrappers which inside actually perform a similar logic like:

// a, b, ... are variable length parameters of different type

void API_Wrapper(hHandle, a, b, ..)
{
if (hHandle)
   return remote_API(hHandle, a, b, ..);
else
   return API(a, b, ..);
}

I want to use a macro to reuse the if-else logic so I can simply implement the function like this:

void API_Wrapper(hHandle, a, b, ..)
{
    API_CALL(api_name, hHandle, a, b, ..); // API_CALL is a macro
}

I didn’t come up with a good way. (Note: I could solve it via … and __va_args__ but this extension is not supported by the compiler we currently use)

Anyone ever met the same problem and any idea?

Answer 1

Another trick, without variadic macro’s:

#define API_CALL(hHandle, api_name, arguments) if (hHandle) return remote_##api_name arguments; else return api_name arguments;

void API_Wrapper(int hHandle, int a, double b, char c)
{
            API_CALL(hHandle, api_name, (a, b, c));
}

Which becomes:

void API_Wrapper(int hHandle, int a, double b, char c)
{
     if (hHandle) return remote_api_name (a, b, c); else return api_name (a, b, c);;
}