Re: deleting a class

On Fri, 2005-04-08 at 12:52, Raymond Martin wrote:
> Of course you cannot delete a class. A class is a declaration that is
> used to instantiate objects. You delete objects, not classes.

Yes. My posting wasn't very clear. My point was that you probably
never want to redefine a class either and therefore want to get
an error if you try to do so--just as when you try to delete a class.


On Fri, 2005-04-08 at 17:23, Leon Bottou wrote: 
> > But then it should 
> > not be allowed to redefine a class either: 
> 
> Redefining means creating a new class with the same name.
> If there were instances of the old class, these instances remain
> associated with the old class.  You can still access the old class ]
> using the <classof> function. 


? (defclass |A| object
       (version "1"))
= |A|
? (defmethod |A| print-version ()
      print version)
= print-version
? (setq a1 (new |A|))
= ::A:978aa80
? (==> a1 print-version)
= "1"
? (defclass |A| object)
= |A|
? (defmethod |A| print-version ()
      print "2")
= print-version
? (==> a1 print-version)
= "1"
? (setq a2 (new |A|))
= ::A:9d4f770
? (==> a2 print-version)
= "2"
? (setq another1 (new (classof a1)))
= ::A:9d4b360
? (==> another1 print-version)
= "1"
?

Makes sense, thanks.


>  When no instances of the old class remain,
> the old class is simply garbage collected.
> 
> Try this:
> ? (pretty (macro-expand (defclass foo object)))

cool.

ralf





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