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Re: COERCE-FROM-TYPE and TYPE-OF
- To: masinter.pa@Xerox.COM
- Subject: Re: COERCE-FROM-TYPE and TYPE-OF
- From: David A. Moon <Moon@STONY-BROOK.SCRC.Symbolics.COM>
- Date: Tue, 13 Sep 88 10:22 EDT
- Cc: Masayuki Ida <ida%cc.aoyama.junet%UTOKYO-RELAY.CSNet@relay.cs.net>, cl-cleanup@SAIL.STANFORD.EDU, email@example.com
- In-reply-to: <880913-023047-2587@Xerox>
- Line-fold: No
Date: 13 Sep 88 02:31 PDT
I think we need a cleanup item to redefine TYPE-OF to be basically (CLASS-NAME
(CLASS-OF x)) with perhaps a few exceptions for vectors and arrays.
I don't entirely agree. CLASS-OF (88-002R pp.1-15 through 1-17) was
carefully defined to require the existence only of built-in classes
on which it is clearly meaningful to put methods in portable programs.
TYPE-OF (CLtL p.53) on the other hand is defined to be for debugging,
not for type-dispatching, and to return as specific an answer as
"convenient and useful." Thus it seems unlikely that people would
really want these two to return the same answer, since they exist for
Also 88-002R (chapter 2) says CLASS-NAME can return NIL.
I would certainly oppose redefining CLASS-OF to have as vague a
definition as TYPE-OF.
If it's proposed to redefine TYPE-OF to be no more specific than
CLASS-OF, I would counter-propose to eliminate TYPE-OF entirely,
since it would be redundant.