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Re: change-class and class redefinition
- To: Moon@STONY-BROOK.SCRC.Symbolics.COM
- Subject: Re: change-class and class redefinition
- From: Gregor.pa@Xerox.COM
- Date: 23 Jan 87 11:40 PST
- Cc: Common-Lisp-Object-System@SAIL.STANFORD.EDU
- In-reply-to: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>'s message of Thu, 22 Jan 87 00:57 EST
Moon says:
However, this is missing the major point. I believe that "copying the
slots" is the wrong model of what is happening. A slot is a conceptual
entity, not a word of computer storage at a particular address. No slot
contents are being copied or changed. Some slots are being deleted,
some other slots are being newly created and therefore initialized, and
the rest of the slots remain unchanged. If a particular implementation
happens to work by moving the representation of a slot from location
1000 to location 1492, that's an implementation detail and not something
the programmer should see. At the level of abstraction that programmers
should deal with, a slot is a slot and nothing is being copied.
I like this argument, and am now happy with the change-class, class-changed part of this.