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@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 - 12:31:39 CDT