OID and PL/pgSQL trigger :-(

Hy all!

I would like to use OIDs as a primary key on every table of my db,
because this seem to me a very smart thing to do..... but after some
experiment, I've decided to create a SERIAL field on every table, and to
use it as the primary key, and to abandon OIDs...

This is an example of what I whould like to write (and I can't):

CREATE FUNCTION firstTable_DelCascade() RETURNS OPAQUE AS '
BEGIN
DELETE FROM anotherTable WHERE anotherTable.OIDfromFirstTable =
OLD.OID;
RETURN OLD;
END;
' LANGUAGE 'plpgsql';

Well, this can't work because OLD is of type RECORD, and type record
have no OID :-(
(this is what I found in the docs, about RECORD:
"Only the user attributes of a table row are accessible in the row, no
Oid or other system attributes (hence the row could be from a view and
view rows don't have useful system attributes)" )

The main question is: can I get the OID of the OLD/NEW record in
triggers?
A more general question is: what is the usefulness of OIDs, if I can't
use them in trigger?

Paolo