Re: what are keys and surrogates?
Date: Thu, 17 Jan 2008 09:40:19 -0400
> On Jan 10, 7:07 am, Bob Badour <bbad..._at_pei.sympatico.ca> 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. Received on Thu Jan 17 2008 - 14:40:19 CET