+ (eval '(and (= (y foo) 456) (= (z foo) 789)) (current-module)))
+
+ (pass-if "changing class"
+ (let* ((c1 (class () (the-slot #:init-keyword #:value)))
+ (c2 (class () (the-slot #:init-keyword #:value)
+ (the-other-slot #:init-value 888)))
+ (o1 (make c1 #:value 777)))
+ (and (is-a? o1 c1)
+ (not (is-a? o1 c2))
+ (equal? (slot-ref o1 'the-slot) 777)
+ (let ((o2 (change-class o1 c2)))
+ (and (eq? o1 o2)
+ (is-a? o2 c2)
+ (not (is-a? o2 c1))
+ (equal? (slot-ref o2 'the-slot) 777))))))
+
+ (pass-if "`hell' in `goops.c' grows as expected"
+ ;; This snippet yielded a segfault prior to the 2008-08-19 `goops.c'
+ ;; fix (i.e., Guile 1.8.5 and earlier). The root of the problem was
+ ;; that `go_to_hell ()' would not reallocate enough room for the `hell'
+ ;; array, leading to out-of-bounds accesses.
+
+ (let* ((parent-class (class ()
+ #:name '<class-that-will-be-redefined>))
+ (classes
+ (unfold (lambda (i) (>= i 20))
+ (lambda (i)
+ (make-class (list parent-class)
+ '((the-slot #:init-value #:value)
+ (the-other-slot))
+ #:name (string->symbol
+ (string-append "<foo-to-redefine-"
+ (number->string i)
+ ">"))))
+ (lambda (i)
+ (+ 1 i))
+ 0))
+ (objects
+ (map (lambda (class)
+ (make class #:value 777))
+ classes)))
+
+ (define-method (change-class (foo parent-class)
+ (new <class>))
+ ;; Called by `scm_change_object_class ()', via `purgatory ()'.
+ (if (null? classes)
+ (next-method)
+ (let ((class (car classes))
+ (object (car objects)))
+ (set! classes (cdr classes))
+ (set! objects (cdr objects))
+
+ ;; Redefine the class so that its instances are eventually
+ ;; passed to `scm_change_object_class ()'. This leads to
+ ;; nested `scm_change_object_class ()' calls, which increases
+ ;; the size of HELL and increments N_HELL.
+ (class-redefinition class
+ (make-class '() (class-slots class)
+ #:name (class-name class)))
+
+ ;; Use `slot-ref' to trigger the `scm_change_object_class ()'
+ ;; and `go_to_hell ()' calls.
+ (slot-ref object 'the-slot)
+
+ (next-method))))
+
+
+ ;; Initiate the whole `change-class' chain.
+ (let* ((class (car classes))
+ (object (change-class (car objects) class)))
+ (is-a? object class)))))