Re: no names allowed, we serve types only

On Feb 20, 10:40 am, David BL <davi..._at_iinet.net.au> wrote:
>
> I agree this provides some motivation, but it doesn't seem sufficient
> justification to "conflate" concerns (as Bob says). The crucial point
> is this: The attribute domains are part of the relation-type, whereas
> the attribute names are part of the relation-value. What happens with
> your suggestion?
>
> It's very important to keep a clear separation between a value and its
> declared type, in order to understand equality. Your suggestion ends
> up conflating relation-type and relation-value.
>
> How do you support sub-typing of relation-types according to sub-
> typing of the attribute domains, and still allow for addressing the
> attributes by type name? It seems you are forced to support multiple
> typenames for an attribute. E.g. a relation has an attribute
> containing circles and you must allow it to be addressed using either
> circle or ellipse.

Oops, I got confused saying "your suggestion". Of course I mean "Keith's suggestion" Received on Sat Feb 20 2010 - 04:15:00 CET