Question

We have an existing function implementation in our C++ code:

void Function(int param)
{
    printf("In Function\n");
}

int main()
{
    Function(10);
    return 0;
}

I wish to change it to call another function (by help of a macro declaration) which would accept additional params like FILE and LINE (for debugging purpose) and then call the actual function:

#define Function(param) Function_debug(param, __FILE__,  __FUNCTION__,  __LINE__) \
{\
    printf("In Function_debug [%s] [%s] [%d]\n", file, func, line); \
    Function(param);\
}

But the below code:

#include <stdio.h>

#define Function(param) Function_debug(param, __FILE__,  __FUNCTION__,  __LINE__) \
{\
    printf("In Function_debug [%s] [%s] [%d]\n", file, func, line); \
    Function(param);\
}

void Function(int param)
{
    printf("In Function\n");
}

int main()
{
    Function(10);
    return 0;
}

Translates TO:

void Function_debug(int param, "temp.cpp", __FUNCTION__, 9) { printf("In Function_debug [%s] [%s] [%d]\n", file, func, line); Function(int param);}
{
    printf("In Function\n");
}

int main()
{
    Function_debug(10, "temp.cpp", __FUNCTION__, 16) { printf("In Function_debug [%s] [%s] [%d]\n", file, func, line); Function(10);};
    return 0;
}

which gives compilation errors.

Please direct me how to achieve the objective?

Answer 1

Normally you’d do something like this:

#if DEBUG
#define FUNCTION(param) Function_debug(param, __FILE__,  __FUNCTION__,  __LINE__)
#else
#define FUNCTION(param) Function(param)
#endif

void Function(int param)
{
    printf("In Function\n");
}

void Function_debug(int param, const char * file,  const char * func,  int line)
{
    printf("In Function_debug [%s] [%s] [%d]\n", file, func, line); \
    Function(param);
}

int main()
{
    FUNCTION(10);
    return 0;
}