Re: Avoiding CLASS-PROTOTYPE

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Article #14

#14

From: Len Charest
Date: Tue, 03 Nov 1992 00:26

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Allow me to follow-up on my own posting:

In article <1992Nov2.214651.18857@jpl-devvax.jpl.nasa.gov>, charest@Aig.Jpl.Nasa.Gov (Len Charest) writes:
|> Problem: given a metaclass CACHING-CLASS that maintains a list of all its direct 
|> instances, how can I create and use a CLASS-PROTOTYPE for a class based on
|> CACHING-CLASS and also, as a special case, ensure that the CLASS-PROTOTYPE does not
|> appear in the metaclass instance list?

I use the generic function CLASS-DIRECT-INSTANCES to access the instance list.
The following :AROUND method on CLASS-PROTOTYPE solves the problem described
above.

(defmethod class-prototype :around ((class caching-class))
  (let ((prototype (call-next-method)))
    (setf (class-direct-instances class)
          (delete prototype (class-direct-instances class) :test #'eq))
    prototype))

..................................................
                                  Len Charest, Jr.
                 JPL Artificial Intelligence Group
                          charest@aig.jpl.nasa.gov

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Message-ID: <1992Nov3.002630.23187@jpl-devvax.jpl.nasa.gov>

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From: charest@Aig.Jpl.Nasa.Gov (Len Charest)
Newsgroups: comp.lang.clos
Subject: Re: Avoiding CLASS-PROTOTYPE
Keywords: class prototype caching metaclass
Message-ID: <1992Nov3.002630.23187@jpl-devvax.jpl.nasa.gov>
Date: 3 Nov 92 00:26:30 GMT
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