Passing Objects to Stored Procedures in SQL Queries: UNREF(REF(o))

Question

To me it seems that passing an object (type) to stored procedure in a SQL query is quite laborious. See:
I created the following simple type:
TYPE LAST AS OBJECT (
id NUMBER
defined a function:
FUNCTION "CHECKLAST" (l LAST)
RETURN NUMBER
AS LANGUAGE JAVA
NAME 'Checker.checkLast(Last) return int';
created a typed table:
CREATE TABLE lastTable OF Last;
inserted some objects:
INSERT INTO lastTable VALUES (1003);
NOW! If want to use the StoredFunction I have to use the following syntax:
SELECT checkLast(DEREF(REF(o)))
FROM lasttable o;
That's not very elegant.
I would expect the follwing to be working:
SELECT checkLast(o)
FROM lasttable o;
Did I do something wrong? Or did Oracle forget to implement the simple syntax?
Even worse, the DEREF(REF(o)) trick does not work for member functions...
Regards,
André

Answer 1

I did some experiments and can now (partly) answer my own question:
Indeed, it is possible to declare a function with a parameter passed as reference:
CREATE OR REPLACE TYPE Point AS OBJECT
ID INT,
MEMBER FUNCTION distance(q IN REF Point) RETURN NUMBER
Unfortunately, it is not possible to use the REF in PL/SQL directly:
CREATE OR REPLACE TYPE BODY Point is
MEMBER FUNCTION distance(q IN REF Point) RETURN NUMBER
AS
BEGIN
RETURN q.ID - SELF.ID; --Error(5,14): PLS-00536: No navigation through REF
END;
end;
So, for testing purposes I decided to implement a very simple PL/SQL member function:
CREATE OR REPLACE TYPE BODY Point is
MEMBER FUNCTION distance(q IN REF Point) RETURN NUMBER
AS
BEGIN
RETURN -1;
END;
end;
BUT: The SQL query without VALUE is still not possible. The query
SELECT *
FROM PointTable d, PointTable e
WHERE d.distance(e) > 0
renders ORA-00904: "E": invalid identifier
Somehow the 'e' seems to be misinterpreted completely.
Illogically, the following query works fine:
SELECT *
FROM PointTable d, PointTable e
WHERE d.distance(REF(e)) > 0
The illogical thing is that, now 'E' seems to refer to a VALUE and not to REF (because we can use the REF function), whereas in Gaverill's post 'O' seems to refer to a REF (because we can use the VALUE function).
My intent is to avoid both the VALUE(o) from Gaverill's example and the REF(e) from my example, because both is not intuitive for end users...
Maybe I have to define a VIEW holding the object values... But then the end user has to use it in the FROM part.
All in all, there seems to be no elegant solution for passing objects as parameters to functions...
Regards,
André