bloggo ergo sum

I wish I could say I came up with the below, and I suppose I did, but I more or less gathered two or three techniques I didn’t come up with into a few lines to code to make a macro useful for debugging. Its primary merits are readable output and extreme ease of use.

#define MY_MODULE_DEBUG_CATEGORY1  0x0001
#define MY_MODULE_DEBUG_CATEGORY2  0x0002
#define MY_MODULE_DEBUG_CATEGORY3  0x0004

#if !defined(MY_MODULE_DEBUG)
#  define MY_MODULE_DEBUG                 0x0000
#endif
#define _pp_string(x) #x
#define _pp_str(x)     _pp_string(x)

#if (__GNUC__ > 3)
#  define dbg(cat, fmt, ...)					\
   do {								\
      if (MY_MODULE_DEBUG_##cat & MY_MODULE_DEBUG)		\
      {								\
	 printf(__FILE__":"_pp_str(__LINE__)" [%s] "fmt,	\
		__func__, ##__VA_ARGS__);			\
      }								\
   } while (0)
#else
#  define dbg(cat, fmt, args...)				\
   do {								\
      if (MY_MODULE_DEBUG_ ## cat & MY_MODULE_DEBUG)		\
      {								\
	 printf(__FILE__":"_pp_str(__LINE__)" [%s] "fmt,	\
		__FUNCTION__ , ##args);				\
      }								\
   } while (0)
#endif
#if defined(_SOME_OS_)
#  define os_err(cat, errval)					\
   do {								\
      char *errstr = 0;						\
      error_string(errval, &errstr, 80, ERR_GET_ALL);		\
      if (errstr)						\
      {								\
	 dbg(cat, "OS ERROR:\n%s\n", errstr);			\
	 free(errstr);						\
      }								\
      else							\
      {								\
	 dbg(cat, "OS ERROR: %#lx - err_string() failed!\n",	\
	     errval);						\
      }								\
   } while (0)
#endif

Notice the “os_err” macro above, for use with OS-specific error string functions. This particular incantation is oriented toward a particular OS I interact with at work (names changed to protect the innocent), but the same idea would be applicable to any system, really.