getting OID from PL/PgSQL AFTER trigger

Howdy,

I'm trying to get the OID of the NEW/OLD rows in an AFTER trigger
implemented in PL/PgSQL. Unfortunately, those end up as records in
the trigger, and I can't just use NEW.oid. Is there any way to do
this? I could do it using a trigger written in C, but I'd rather not
have to carry around a C .so just for this.

Note that I effectively have no knowledge of the format of the record
that's passed in new/old, so I can't either add a sequence or use some
already existing primary key to identify the row uniquely. One quick
hack is to "INSERT INTO dummy VALUES (NULL);" and then GET DIAGNOSTICS
z = RESULT_OID; and then use z - 1, but that will get me into lots of
trouble with multiple cilents accessing the database. :-)

For the time being, I'm going to implement the trigger in C, but I'm
open to suggestions on how to implement this in straight PL/PgSQL.

Thanks in advance,
- Vlad