Re: OO and relation "impedance mismatch"

"Laconic2" <laconic2_at_comcast.net> wrote in message news:-8udnfW9E66vGP3cRVn-uA_at_comcast.com...
>
> "Marshall Spight" <mspight_at_dnai.com> wrote in message
> news:Ms_7d.301694$mD.88577_at_attbi_s02...
>
> > But perhaps the point you are making implicitly is one I'll make
> > explicitly: OO languages have been far and away the most successful
> > at providing programmers with user-defined types of any approach
> > thus far. (And I'd put SQL and existing SQL database as down near
> > the bottom of the list.) Yes, much of OO is still ad-hoc and not
> > well grounded, but doesn't mean it hasn't been spectacularly
> > successful. And it also doesn't mean it isn't on its way to being
> > well-grounded.
>
> Can you explain to me why "CREATE DOMAIN" doesn't cause to to rank SQL a
> little higher?

For exactly and precisely the reason that I don't know anything about it... :-)

Okay, now I've googled it and see it first appears in Postgres in v. 7.4.

> I understand that user defined domains don't define any operators, and all
> domains are subsets of the original primitive dataypes, but it's been
> awfully useful to me in my work!

This certainly does look to be useful, but it's missing some important features relative to objects. IIUC, you can't put two ints together to make a point, for example, and you can't define methods. This would not even qualify it as the weaker "object based".

Marshall Received on Mon Oct 04 2004 - 05:00:02 CEST