Re: Clean Object Class Design -- Circle/Ellipse

bbadour_at_golden.net (Bob Badour) wrote in <c14b7.231$5I2.20228238_at_radon.golden.net>:

>Date argues that the type support of the DBMS must allow one to model a
>circle domain as a sub-type of an ellipse domain and you assume he
>claims one MUST model it that way. Likewise, the DBMS must allow one to
>model an integer as a sub-type of real, but that does not require you to
>do so.

Distinction understood.

>The fact that one can define the name Integer to represent a different
>set of numbers and to define the + symbol to have different behavior
>than addition does not prove anything about Date's understanding.

You're right, the fact that one can define the name Integer to represent a different set proves nothing about Date's understanding. This is not what was suggested however. The exact same sets of reals and integers with the exact same operations of addition and multiplication were used.

>Your claims regarding Date's understanding of type are extraordinary,
>incorrect and ad hominem. If you are going to make such an extraordinary
>claim, you must provide extraordinary proof, and you have failed to do
>so. Now, put up or shut up!

I'd like to get away from discussing Date's understanding or lack of it. Can't we just talk about whether we think a decent OO type system should allow (not force) the integers to be a subtype of the reals and why that would be useful?

Martijn Received on Sun Aug 05 2001 - 12:14:19 CEST