gistfile1.lisp

(let* ((class (find-class 'ztesch))
       (class1 (fare-mop:remake-object 
                class
                :direct-slots 
                `((:name bar
                         :readers (bar)
                         :writers nil
                         :initargs (:bar)
                         :initfunction ,(constantly nil)
                         :initform nil)
                  ,@(mapcar
                     (lambda (x)
                       `(:name 
                         ,(c2mop:slot-definition-name x)
                         :writers 
                         ,(c2mop:slot-definition-writers x)
                         :initargs
                         ,(c2mop:slot-definition-initargs x)
                         :initfunction 
                         ,(c2mop:slot-definition-initfunction x)
                         :initform
                         ,(c2mop:slot-definition-initform x)))
                     (c2mop:class-direct-slots class))))))
  (write-line "-----------------------------")
  (describe (make-instance class1 :bar 42))
  (write-line "-----------------------------")
  (describe (change-class (make-instance class1 :bar 42) class)))
;>>  -----------------------------
;>>  #<ZTESCH {10151E9473}>
;>>    [standard-object]
;>>  
;>>  Slots with :INSTANCE allocation:
;>>    BAR  = 42
;>>    FOO  = NIL
;>>  -----------------------------
;>>  #<#<STANDARD-CLASS ZTESCH> {10151EC443}>
;>>    [standard-object]
;>>  
;>>  Slots with :INSTANCE allocation:
;>>    FOO  = NIL
;>>  
;=>  <no values>