tests/mop-32.impure.lisp

   1 ;;;; Handling errors in UPDATE-INSTANCE-FOR-REDEFINED-CLASS
   2
   3 ;;;; This software is part of the SBCL system. See the README file for
   4 ;;;; more information.
   5 ;;;;
   6 ;;;; While most of SBCL is derived from the CMU CL system, the test
   7 ;;;; files (like this one) were written from scratch after the fork
   8 ;;;; from CMU CL.
   9 ;;;;
  10 ;;;; This software is in the public domain and is provided with
  11 ;;;; absolutely no warranty. See the COPYING and CREDITS files for
  12 ;;;; more information.
  13
  14 (defclass foo-class (standard-class) ())
  15
  16 (defmethod sb-mop:validate-superclass ((c foo-class) (s standard-class)) t)
  17
  18 (defclass foo-object (standard-object) ())
  19
  20 (defmethod shared-initialize :around ((class foo-class) slot-names
  21                                       &rest rest
  22                                       &key direct-superclasses)
  23   (apply #'call-next-method
  24          class slot-names
  25          :direct-superclasses
  26          (append (remove (find-class 'standard-object) direct-superclasses)
  27                  (list (find-class 'foo-object)))
  28          rest))
  29
  30 (defmethod update-instance-for-redefined-class :before
  31     ((instance foo-object)
  32      added-slots discarded-slots
  33      property-list
  34      &rest initargs)
  35   (declare (ignore initargs))
  36   ;; This U-I-F-R-C is meant to always signal an error.
  37   (error "expected failure"))
  38
  39 ;;; Define FOO.
  40 (defclass foo () () (:metaclass foo-class))
  41
  42 ;;; Make an instance of FOO.
  43 (defparameter *foo* (make-instance 'foo))
  44
  45 ;;; Redefine FOO, causing *FOO* to become obsolete.
  46 (defclass foo ()
  47   ((slot :initform 42))
  48   (:metaclass foo-class))
  49
  50 ;;; This should result in an "expected failure" error, because
  51 ;;; the instance is obsolete.
  52 (multiple-value-bind (result error)
  53     (ignore-errors (slot-value *foo* 'slot))
  54   (assert (null result))
  55   (assert (string= (princ-to-string error) "expected failure")))
  56
  57 ;;; This should *also* result in an "expected failure" error, because after
  58 ;;; the previous U-I-F-R-C call made a non-local exit, the instance should be
  59 ;;; automatically made obsolete once more.
  60 (multiple-value-bind (result error)
  61     (ignore-errors (slot-value *foo* 'slot))
  62   (assert (null result))
  63   (assert (string= (princ-to-string error) "expected failure")))
  64
  65 ;;; Redefine the U-I-F-R-C method to no longer signal an error.
  66 (defmethod update-instance-for-redefined-class :before
  67     ((instance foo-object)
  68      added-slots discarded-slots
  69      property-list
  70      &rest initargs)
  71   (declare (ignore initargs)))
  72
  73 ;;; Instance is now updateable. It should now be possible to access the new slot
  74 ;;; and fetch its initform-initialized value.
  75 (assert (= 42 (slot-value *foo* 'slot)))