Re: Principle of Orthogonal Design

On 9 jan, 02:51, JOG <j..._at_cs.nott.ac.uk> wrote:
> I was wondering what your current stances towards the principle of
> current design is cdt - info about the POOD is actually pretty sparse
> on google, which has not helped my own understanding. I gather that
> Date has realigned his opinion - although what to I know not - and
> that Darwen rejected the original POOD paper outright given that
> McGovern posits that:
>
> R1 { X INTEGER, Y INTEGER }
> R2 { A INTEGER, B INTEGER }
>
> violates the principle, whatever the relations' attribute names.
> Instinctively it does seem rather odd that a predicates such as:
>
> * on Day:X the shop had noCustomers:Y
> * on Roll:A, the dice showed the Number:B
>
> cannot share the same database. Have I interpreted the debate
> correctly? Any insights or corrections are, as ever, appreciated -
> POOD is certainly thought provoking, and the concept that an update
> need not require specifcation of a table name is an interesting one.

My understanding is that the debate centers around typing.

Date advocates strong typing: ie X is of type "shop number" and A is a "roll number", both represent different aspects of the UOD so they have a different type (I disregard subtyping here for simplicity), *even if* the actual underlying representations (e.g. natural numbers) would be the same. Having different types, means the type engine can distinguish them.

DM Unseen Received on Wed Jan 09 2008 - 13:49:57 CET