[armedbear-devel] reinitialize-instance on class metaobjects incorrect

[Rudolf Schlatte]

On Dec 3, 2012, at 01:03, Pascal Costanza <pc at p-cos.net> wrote:

> Hi,
> 
> Consider the following test case:
> 
> CL-USER(1): (use-package :mop)
> T
> CL-USER(2): (defclass a () ())
> #<STANDARD-CLASS A {794563AA}>
> CL-USER(3): (defclass b (a) ())
> #<STANDARD-CLASS B {62F6FB59}>
> CL-USER(4): (finalize-inheritance (find-class 'a))
> NIL
> CL-USER(5): (finalize-inheritance (find-class 'b))
> NIL
> CL-USER(6): (class-precedence-list (find-class 'b))
> (#<STANDARD-CLASS B {62F6FB59}> #<STANDARD-CLASS A {794563AA}> #<STANDARD-CLASS STANDARD-OBJECT {23309E87}> #<BUILT-IN-CLASS T {100C62C8}>)
> CL-USER(7): (reinitialize-instance (find-class 'b))
> #<STANDARD-CLASS B {62F6FB59}>
> CL-USER(8): (class-precedence-list (find-class 'b))
> (#<STANDARD-CLASS B {62F6FB59}> #<STANDARD-CLASS STANDARD-OBJECT {23309E87}> #<BUILT-IN-CLASS T {100C62C8}>)
> 
> The invocation of reinitialize-instance obviously reinitialized the direct-superclasses slot, and thus removed the superclass a.
> 
> However, according to the HyperSpec, the general protocol for reinitialize-instance is always that slots for which no initargs are provided through reinitialize-instance should be left untouched. This also restated implicitly in the CLOS MOP specification, for example in the section "Initialization of Class Metaobjects:" The defaulted superclass list is specified to be only assigned during initialization, but not during reinitialization.

Thanks, logged at http://trac.common-lisp.net/armedbear/ticket/277

Rudi