Re: more closed-world chatter

From: paul c <toledobythesea_at_oohay.ac>
Date: Sun, 06 May 2007 17:12:23 GMT
Message-ID: <X%n%h.163039$6m4.100442@pd7urf1no>

paul c wrote:
> Jon Heggland wrote:
>

>> Marshall wrote:
>>
>>> On May 5, 8:50 am, Jon Heggland <jon.heggl..._at_idi.ntnu.no> wrote:
>>>
>>>>> when it comes to the advantage of sub-typing in dealing with
>>>>> my question.
>>>>
>>>>
>>>> I don't know about "advantage"; I just don't see how you can avoid it.
>>>
>>>
>>> It's easy to avoid: just don't put subtying in the language design.
>>
>>
>>
>> I didn't mean how to avoid subtyping per se; I meant how to avoid it if
>> you want to be able to join on attributes with different types.

>
>
> Not to distract my betters on this topic, but I guess I should have
> originally mentioned that I think the D&D stipulation "It is required
> that if <A,T1> is in Hr1 and <A,T2> is in Hr2, then T1 = T2" could be
> gotten around simply by ensuring that no two relvars have such an
> attribute. ...

Just in case that wasn't clear, I meant "by ensuring there is no attribute in two different relations that doesn't have the same type in both".

p Received on Sun May 06 2007 - 12:12:23 CDT