blake at mcbride.name
Wed Mar 10 22:29:05 UTC 2010
On Wed, Mar 10, 2010 at 2:12 PM, Alessio Stalla <alessiostalla at gmail.com> wrote:
> On Wed, Mar 10, 2010 at 8:50 PM, Blake McBride <blake at mcbride.name> wrote:
>> (slot-value (make-instance 'class1) 'cv2)
>> creates an instance.
> Sure, but (slot-value (mop::class-prototype (find-class 'class1))
> 'cv2) does not and still fails with a slot-missing error, which was my
>> He wanted access to a true class variable,
> no, he wanted to "access class-allocated slot values" in his own
> words. This, in the context of CL, can only mean slots with
> :allocation :class.
>> stored in the class (class1) that was accessible via a class
>> reference. If that's what he wanted, that's exactly what my code
>> My example code does store cv? in class1, not the meta-class.
> It's perfectly fine, but cv? are not class-allocated slots, at least
> not as the CL standard defines them.
A class defines what (instance) variables are in instances of itself.
A metaclass defines what (class) variables are defined in its
instances (the class). Therefore, semantics aside, a metaclass
defines what (class) variables are _stored_ in the class itself - not
the meta class, and not instances of the class. My example does in
fact store the class variables in the class and not in the metaclass
since the metaclass defines what variables are in its instances - the
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