return value of the trigger function

Hi

I have big problem with a trigger function.
Defs:

CREATE TABLE foo (id int2, name varchar(20));

foo.id cannot be serial or autoint because it will not be unique.

Now I need a trigger that return foo.id of the inserted record.

INSERT INTO foo VALUES (max(foo.id)+1,'junk');


IMHO the trigger should be:

CREATE TRIGGER tr_get_new_id
AFTER INSERT on foo
ON EACH ROW
EXECUTE PROCEDURE get_new_id();

But I cannot create the function :(
I don't know what type should be input and how about output? trigger or 
int2?

TIA,


-- 
Jarek Pudelko
JP272-RIPE