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- Path: sparky!uunet!mcsun!julienas!corton!ilog!davis
- From: davis@passy.ilog.fr (Harley Davis)
- Newsgroups: comp.object
- Subject: Re: FAQ Part 1 (of 2) [ objects, closures, continuations ]
- Message-ID: <DAVIS.93Jan22105234@passy.ilog.fr>
- Date: 22 Jan 93 09:52:34 GMT
- References: <1993Jan13.061114.18430@netcom.com> <PCG.93Jan14154212@decb.aber.ac.uk>
- <1993Jan15.033713.27130@netcom.com> <PCG.93Jan19235921@decb.aber.ac.uk>
- Sender: news@ilog.fr
- Organization: ILOG S.A., Gentilly, France
- Lines: 42
- In-reply-to: pcg@aber.ac.uk's message of 19 Jan 93 23:59:21 GMT
-
-
- In article <PCG.93Jan19235921@decb.aber.ac.uk> pcg@aber.ac.uk (Piercarlo Grandi) writes:
-
- (Bob Hathaway) said:
-
- pcg> More precisely objects are values of a procedure instance
- pcg> (closure/continuation) record type.
-
- objsys> Since the FAQ will typically be for newcomers, could you please
- objsys> put the last sentence in English and/or give references?
-
- The references are easily produced: "Hierarchical Program Structures",
- in "Structured Programming", Academic Press, and "Structure and
- Interpretation of Computer Programs", MIT Press.
-
- In particular they show that (in class based OO languages) classes are
- procedures, and objects are procedure instances; closures if the
- language is a traditional OO one, and continuations if the language is
- an actor OO one.
-
- Classes and objects are not procedures; rather, they can be
- implemented or, perhaps, thought of as procedures in some languages
- for some OO models. Two reasons:
-
- 1. In latently typed languages with first-class procedures, most
- objects (except for real procedures) will return false when asked
- if their type is procedure.
-
- 2. The simplistic SICP OO implementation in terms of closures does not
- account for multi-methods.
-
- Also, what is the difference between a "procedure" and a "procedure
- instance"? Perhaps you meant to say that a class can be thought of as
- a procedure which returns procedures.
-
- -- Harley Davis
- --
-
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- nom: Harley Davis ILOG S.A.
- net: davis@ilog.fr 2 Avenue Gallie'ni, BP 85
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