[HACKERS] Enum type emulation: problem with opaque type in PL/pgSQL functions

[Max Fonin]

Guys, hello.

Here is a problem.

--
-- Creating 2 new functions and new type
--
BEGIN;

CREATE FUNCTION enum_week_in (opaque)
        RETURNS int2
        AS '
        DECLARE
            invalue ALIAS for $1;
        BEGIN
                IF invalue='''' OR invalue=''0'' THEN RETURN 0; END IF;
                IF invalue=''Monday'' OR invalue=''1'' THEN RETURN 1; END IF;
                IF invalue=''Tuesday'' OR invalue=''2'' THEN RETURN 2; END IF;
                IF invalue=''Wednesday'' OR invalue=''3'' THEN RETURN 3; END IF;
                RAISE EXCEPTION ''incorrect input value: %'',invalue;
        END;'
        LANGUAGE 'plpgsql'
        WITH (ISCACHABLE);

CREATE FUNCTION enum_week_out (opaque)
        RETURNS text
        AS '
        DECLARE
            outvalue ALIAS for $1;
        BEGIN
                IF outvalue=0 THEN RETURN ''''; END IF;
                IF outvalue=1 THEN RETURN ''Monday''; END IF;
                IF outvalue=2 THEN RETURN ''Tuesday''; END IF;
                IF outvalue=3 THEN RETURN ''Wednesday''; END IF;
                RAISE EXCEPTION ''incorrect output value: %'',outvalue;
        END;'
        LANGUAGE 'plpgsql'
        WITH (ISCACHABLE);

CREATE TYPE enum_week (
        internallength = 2,
        input = enum_week_in,
        output = enum_week_out,
        PASSEDBYVALUE
);

COMMIT;

Well, all is ok after it, e.g. functions and type were registered in system catalog.

Now, when I try to do "SELECT enum_week_in('Monday')", I get the following:

NOTICE: plpgsql: ERROR during compile of enum_week_in near line 0

The same will occure if I

CREATE TABLE test (wday enum_week);
insert into test (wday) values ('Monday')

If I redefine the same functions with input argtype 'text'/'int2' they work fine.
I guess the problem is that PL/pgSQL doesn't handle opaque type correctly.

Any ideas ?

I don't care how but I need to emulate ENUM type, just to convert MySQL dumps to 
PostgreSQL. E.g. ENUM values 
stored in MySQL dump should be restorable in Postgres without any conversion.

I running PostgreSQL 7.0.3 on Linux RedHat 6.2, kernel 2.2.15, Intel Celeron CPU; 
Postgres was 
upgraded from 7.0.2 without changing anything in system catalog.

Thanks,
Max Rudensky.