johnpitcairn

Paranoia dept: what would be the most reliable way to check that a non-NIL pointer bound to a symbol's s_thing field is a t_linklist?

checking-for-valid-t_linklist-bound-to-symbol-s_thing

A common way to do this in C would be to have a 'magic number' in the linklist type, right? I don't see anything like that in the API..

if (!NOGOOD(o) && ob_sym(o) == gensym("linklist")) {

This will test for the magic number/object validity, and then verify that it's the class you want.

if (!NOGOOD(o) && ob_sym(o) == gensym("linklist")) {
  // it's a linklist
}

This will test for the magic number/object validity, and then verify that it's the class you want.


Great, thanks. I was thinking I'd need to make a custom struct containing the t_linklist and my own magic number field. So this technique is applicable to any t_object?

Yeah, as long as you know the object's class name.

Checking for valid t_linklist bound to symbol s_thing