- /*
- There is no mutable prop yet, so create an entry, and put it in front of the
- mutable prop list.
- */
- handle = scm_sloppy_assq (sym, immutable_property_alist_);
- SCM tail = (handle != SCM_BOOL_F) ? gh_cdr(handle) : SCM_EOL;
- SCM val = gh_cons (thing, tail);
-#ifndef HASHING_FOR_MUTABLE_PROPS
- mutable_property_alist_ = gh_cons (gh_cons (sym, val),
- mutable_property_alist_);
-#else
- scm_hashq_set_x (mutable_property_alist_, sym, val);
-#endif
+ Grob *me = ((Grob*)this);
+ val = me->try_callback_on_alist (&me->mutable_property_alist_, sym, val);