Richard M Kreuter wrote:
> Two reasons.
> First, the slot in your condition are not named :FIELD1 and :FIELD2,
> but FIELD1 and FIELD2, so those calls to SLOT-VALUE won't work on any
> instances with slots so named:
I changed FIELD1 to :FIELD1 - no result.
> Second, SLOT-VALUE has no specified semantics for instances of
> condition classes , so you shouldn't expect this code to be
> portable, even if it happened to work on some implementation. Just
> define a couple of readers.
> Hope that helps,
>  http://www.lisp.org/HyperSpec/Body/fun_slot-value.html
Oops, You are right. Many thanks!
WBR, Yaroslav Kavenchuk.