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- To: gregor.pa@Xerox.COM
- Subject: RE:metaclass
- From: Jacky Combs <combs@STC.LOCKHEED.COM>
- Date: Mon, 30 Jan 89 13:28:59 CST
- Cc: commonloops.pa@Xerox.COM
- Redistributed: commonloops.pa
Thanks for responding to my metaobject query, but I still have a question.
I have no problem with PCL's "compatibility checking" in the metaobject
protocol, but to say that defining a corresponding
check-super-metaclass-compatibility method is all that one needs to do in order
to define another metaclass is a bit misleading. For example if the new
metaclass is to be redefined correctly one needs to also define the necesary
My question is, other than the source code, how can I find out what PCL's
design of the metaobject protocol is? It is my understanding that Chapter
Three (MetaObject Protocol) of the CLOS Specifications is not available. Since
defining metaclasses in PCL seems to be a poorly understood task right now, it
would really help to have some general information about the topic.
I realize that the specific behavior of a user-defined metaclass dictates what
some of the method definitions must be. For example I have defined the
metaclass EXTENSION-META for classes that maintain a list of their current
instances; therefore I needed to add methods to *make-instance,
update-instances-for-different-class, and update-instances-for-redefined-class.
Any information on metaobject creation would be most helpful. Thanks.