wrangling CPP into being a codegen...

/* run this through CPP to see what this is all about */
  
/* this would be a separate include file but for simplicity we leave it here */

#define CAT(a, ...) PRIMITIVE_CAT(a, __VA_ARGS__)
#define PRIMITIVE_CAT(a, ...) a ## __VA_ARGS__

#define EXCEPTION_CHECK_N(x, n, ...) n
#define EXCEPTION_CHECK(...) EXCEPTION_CHECK_N(__VA_ARGS__, USUAL_HANDLING,)
#define DEFAULT_EXCEPTION SPECIAL_PROC(~)
#define SPECIAL_PROC(x) x, EXCEPTION_HANDLING,
#define SPECIAL_EXCEPTION(x) 1, x

#define HANDLING(x) EXCEPTION_CHECK(PRIMITIVE_CAT(EXCEPTION_, x))

/* include the above... then, define these: */

#define EXCEPTION_asd SPECIAL_EXCEPTION({ int baz; printf("Exceptional exception handling\n"); })
#define EXCEPTION_def DEFAULT_EXCEPTION
#define EXCEPTION_xxxx SPECIAL_EXCEPTION({ int baz2; printf("Exceptional exception handling #2\n"); })
#define USUAL_HANDLING { int usual; printf("This is business as usual\n"); }
#define EXCEPTION_HANDLING { int bar; printf("This is a default exception\n"); }

/* and then code-generate.... */

HANDLING(asd)
HANDLING(def)
HANDLING(xxxx)
HANDLING(whatever)
HANDLING(some_other_whatever)