Re: what are keys and surrogates?

From: Jan Hidders <>
Date: Thu, 17 Jan 2008 12:45:48 -0800 (PST)
Message-ID: <>

On 17 jan, 14:40, Bob Badour <> wrote:
> Marshall wrote:
> > On Jan 10, 7:07 am, Bob Badour <> wrote:
> >>Marshall wrote:
> >>>>Is "constructor" the same as what C. Date calls a "selector"?
> >>>Yes. Date calls it a selector, and the entire rest of the world
> >>>calls it a constructor. :-)
> >>Except "selector" has no concept of physically building anything in storage.
> > Okay. Just specifying a value, or a kind of value, yes?
> > That's more or less what I understand the most general
> > definition of the word "constructor" to mean. The OOP
> > world uses it a bit more specifically.
> I suspect the word originates in the OOP world, and it strongly suggests
> building something physical.
> >>>I have no strong feelings about encapsulated ADTs; what
> >>>Date calls ... uh. Shit. I can't remember what he calls them.
> >>>I don't entirely see the reason for them. Performance I guess?
> >>Types? Possible representations? Type generators? Only the first is an
> >>ADT, but I am curious whether you meant one of the others.
> > Possreps! That's the one!
> Having multiple possible representations for the same type allows data
> independence--especially physical independence.

You think the number of possible representations and the number of possible ways to store something in memory or on disk are related? Why?

  • Jan Hidders
Received on Thu Jan 17 2008 - 21:45:48 CET

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