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Re: Date's First Great Blunder

From: Tom Hester <$$tom_at_metadata.com>
Date: Wed, 14 Apr 2004 12:13:30 -0700
Message-ID: <5b400$407d8d61$45033832$1892@msgid.meganewsservers.com>


Weren't we just here a couple of weeks ago. The answer is that a class is not a domain and a class is not a relvar. Who knows what a counterpart is? My suggestion is that we all go home tonight and read Feyerabend.

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c5ia56$t04$1_at_news.netins.net...
> C. J. Date has written about what he calls "The First Great Blunder"
related
> to this question: What concept is it in the relational world that is the
> counterpart to the concept of object class in the object world?
>
> He suggests that there are two answers given: domain = object class or
> relvar = object class. He then says that the first equation is obviously
> right and the second wrong. Classes are types and domains are types, but
> relvars are variables and, therefore, not types, so QED.
>
> The idea, it seems, is to rid Java programmers of the notion of using
> classes to define "relations" or records. I'm guessing I'm not the only
one
> who doesn't buy Mr. Date's argument.
>
> I'll toss out one of the way-too-many-thoughts buzzing in my head on this
> topic. How about this equation:
>
> Class = Metadata
>
> A class is a spec/template -- not a variable nor an object. There can be
> metadata for a type and metadata for a relation/record and classes
> corresponding to either.
>
> Do many folks agree with Date on this point or is this one of his
> lone-ranger attempts to push against the OO folks? --dawn
>
>
Received on Wed Apr 14 2004 - 14:13:30 CDT

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