(defclass a (b)) (make-instance 'a) ; Evaluation aborted on NIL. ;; no backtrace in slime The problem is that b is not defined, but the error makes this difficult to discern.
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Trying to fix the problem in some ways leads to more:
(defclass a1 (b1)) (defclass b2 ()) CL-USER> (make-instance 'a1) ; Evaluation aborted on NIL. ;; no backtrace in slime CL-USER> (defclass a1 (b2)) ; Evaluation aborted on NIL. ;; no backtrace in slime ---
(defclass a3 (b3)) (mop::class-prototype (find-class 'a3)) ;; here we get a backtrace: #<STANDARD-CLASS A3 {1E8E471}> is not finalized.
However it is hard to figure out what the problem is.
Now try to fix it:
(defclass b3 ()) (mop::class-prototype (find-class 'a3)) ;; still get "is not finalized" error (make-instance 'a3) ;; succeeds (mop::class-prototype (find-class 'a3)) ;; now it succeeds
-Alan