Re: The IDS, the EDS and the DBMS
From: mAsterdam <mAsterdam_at_vrijdag.org>
Date: Wed, 08 Sep 2004 19:31:39 +0200
Message-ID: <413f41fd$0$37789$e4fe514c_at_news.xs4all.nl>
>
> There's that number 3 again. It keeps cropping up. For me, there are
> three things you can do with data:
> You can process data. You can store data. And you can transmit data.
> Almost anything that adds value to data is a blend of all three of these.
>
>
> I guess I don't really understand the difference between type implementation
> and integrity enforcement.
>
> A type definition defines the elements, their representations, and the
> operations defined over them. Isn't this a form of integrity? Or am I
> missing something?
Date: Wed, 08 Sep 2004 19:31:39 +0200
Message-ID: <413f41fd$0$37789$e4fe514c_at_news.xs4all.nl>
Laconic2 wrote:
> What is ADT?
Date and Darwen, The Third Manifesto (first printing), p102
"A /note on terminology/: User defind data types (UDTs for short) are sometimes called /abstract/ data types (ADTs) in the literature; we prefer not to use this term, however, in part we believe a good argument could be made that /all/ types are (or should be) "abstract," in the sense that their representation is hidden." (italics original)
>>...the "ultimate language" will use Third-Manifesto >>O-O concepts for types, relations for data manipulation, >>and first-class functions for... well, I'm not sure, or >>I'd have written the damned thing by now. But I think >>those 3 concepts are all critical to development.
>
> There's that number 3 again. It keeps cropping up. For me, there are
> three things you can do with data:
> You can process data. You can store data. And you can transmit data.
> Almost anything that adds value to data is a blend of all three of these.
>
>>>Consider what one uses encapsulation for: >>>to enforce certain invariants in data structures. >>>Isn't declarative integrity constraints a uniformly >>>superior mechanism for doing that? >> >>Yes, exactly. >> >>>If there is more to encapsulation >>>than enforcing integrity, I'm not aware of it. >> >>Type implementation; I think Date had it right in suggesting that type >>implementations could be done in a variety of languages, and even that >>those languages might be different than those used in the rest of the >>app...
>
> I guess I don't really understand the difference between type implementation
> and integrity enforcement.
>
> A type definition defines the elements, their representations, and the
> operations defined over them. Isn't this a form of integrity? Or am I
> missing something?
Not saying you are, checking the type of a value *is* somewhat special: You don't need any other time-variant data to do it. Received on Wed Sep 08 2004 - 19:31:39 CEST