+#define ESCAPE_NULL(str) ((str) == NULL ? "(null)" : (str))
+
+#define DEBUG_CALLBACK(shortvar, var, arguments, value) \
+ DBG("shortvar = %s, var = %s, arguments = %s, value = %s, ...", \
+ ESCAPE_NULL(shortvar), \
+ ESCAPE_NULL(var), \
+ ESCAPE_NULL(arguments), \
+ ESCAPE_NULL(value))
+