thanks, but my question is something like this:
...
(cache ... #:slot-ref (lambda (o) (slot-ref o 'cache)) ...) ;; ERROR
...
(sunday ... #:slot-ref (lambda (o) (slot-ref o 'cache)) ...) ;; That's OK

I could call "(slot-ref o 'cache)" in other slot except "cache", but what
should I do if I need to use "(slot-ref o 'cache)" in the "cache"
definition?
I used it directly and got "stack overflow". I think it may cause infinite
recursive.
Actually my question can be described more explicitly: "Can I just re-define
"slot-ref" or "slot-set!" any one of them but NOT both?"
Sometimes I may need a re-defined "slot-set!" but I expect to let alone
"slot-ref".
Anybody catch my mind?