Re: Principle of Orthogonal Design
Date: Tue, 22 Jan 2008 21:36:08 GMT
Message-ID: <cltlj.3537$uB6.1466_at_trndny05>
"JOG" <jog_at_cs.nott.ac.uk> wrote in message
news:87fece57-0892-4a5f-b3c0-a06c03ccc85b_at_e4g2000hsg.googlegroups.com...
> On Jan 22, 7:07 pm, "David Cressey" <cresse..._at_verizon.net> wrote:
> > But "home phone number // work phone number" sure looks like gen-spec
to
> > me.
> > "phone number" is data that can be applied to a "telephone"
generically.
> > a "home phone" is a specialized phone. (Actually, it isn't the
telephone,
> > but the telephone line or more specifically the associated service
contract,
> > that is peculiar to either home or work).
>
> Keep your dastardly OO away from my query neutral data, and leave it
> in Smalltalk where it belongs ;)
>
I plead not guilty. ER modeling sometimes has the gen-spec pattern added to
the other patterns.
See the U Texas data modeling website.
> Given:
We don't need "numbers" in the context of this discussion.
> - Frank's home telephone number is X
> - Franks work telephone number is Y
> - Tom's home telphone number is Z
>
What's not clear to me is whether we have any attributes that are unique to home phones or to work phones.
That depends on the U of D. Also, "Frank's work telephone number is Y"
might really mean "Frank can be reached, at work, at telephone number Y".
Oops, I forgot. We aren't supposed to be discussing meaning.