Question

I wrote a logging mechanism with several log levels.

LOG_FATAL(s)
LOG_ERROR(s)
LOG_WARN(s)
...

Now I want to be able to activate or deactivate the logging for some modules.
What I do now:

#ifdef MOUDLE_LOG_ON
  MODULE_LOG_FATAL(s)  LOG_FATAL(s) 
  MODULE_LOG_ERROR(s)  LOG_ERROR(s)
  MODULE_LOG_WARN(s)   LOG_WARN(s)
  ...
#else
  MODULE_LOG_FATAL(s) 
  MODULE_LOG_ERROR(s)
  MODULE_LOG_WARN(s)
  ...
#endif

Is there a way to place the prefixing in a macro to use it like this:

SETUPLOGGING(MODULE) 

Answer 1

I am wondering if using macros and inline functions could solve your issue:

void inline LOG_FATAL(const char *s)
{
    printf("%s\n", s);
}

#define SETUPLOGGING(x) \
    void inline x ## _LOG_FATAL(const char *s) { LOG_FATAL(s); }

SETUPLOGGING(MODULE)

int main()
{
    MODULE_LOG_FATAL("hello");
}

After preprocessing, this produces:

void inline LOG_FATAL(const char *s)
{
 printf("%s\n", s);
}

void inline MODULE_LOG_FATAL(const char *s) { LOG_FATAL(s); }

int main()
{
 MODULE_LOG_FATAL("hello");
}