Dynamic access to record fields in PL/pgSQL

PL/pgSQL isn't dynamic language. Usually it isn't problem. This language is best as glue of SQL statements. One typical feature is strongly static access to record or row fields. But sometime we need dynamic access. This is very hard task in older version. Some better situation is in 8.4, and maybe in 8.5, this problem is definitely out. New an enhancing of hstore module allows conversion from ROW type to hstore type (this is similar to hash table in Perl). We could to use this functionality:

postgres=# SELECT * FROM foo;
 a  | b  |   c    
----+----+--------
 10 | 20 | Pavel
 30 | 40 | Zdenek
(2 rows)

postgres=# select (each(hstore(foo))).* from foo;
 key | value  
-----+--------
 a   | 10
 b   | 20
 c   | Pavel
 a   | 30
 b   | 40
 c   | Zdenek
(6 rows)

CREATE OR REPLACE FUNCTION trgfce() 
RETURNS trigger AS $$
DECLARE r record; 
BEGIN 
  FOR r IN SELECT (each(hstore(NEW))).* 
  LOOP 
    RAISE NOTICE 'key:%, value: %', r.key, r.value; 
  END LOOP; 
  RETURN new; 
END
$$ LANGUAGE plpgsql;

CREATE TRIGGER trg BEFORE INSERT ON foo FOR EACH ROW EXECUTE PROCEDURE trgfce();

postgres=# INSERT INTO foo VALUES(80,90,'Zbynek');
NOTICE:  key:a, value: 80
NOTICE:  key:b, value: 90
NOTICE:  key:c, value: Zbynek
INSERT 0 1