Function To Log Changes

Hi All, I have been tinkering with a function to log the changes made on
any column through a function and trigger.  However, I cant think of a way
to make this work through pl/pgsql.  Any one have any ideas, or is it just
not possible?

SNIP
create or replace function logchange2() returns OPAQUE as '
DECLARE       columnname record;       c2 VARCHAR(64);

BEGIN

/* Cycle through the column names so we can find the changes being made */
FOR columnname IN SELECT attname FROM pg_attribute, pg_type       WHERE attnum > 0 AND typrelid=attrelid AND
typname=''SOMETABLE''LOOP
 
       c2 := CAST(columnname.attname AS VARCHAR(64));
/* here lies the problem.  How would I make plpgsql see OLD.columnname in
a dynamic fashion.  I know this wont work whats below, but I am just
trying to express what I am trying to do */       IF ''OLD.'' || c2 != ''NEW.'' || c2 THEN               /* IF CHANGED
DOSOMETHING */               RAISE NOTICE ''Update on column %'', c2;       END IF;
 

END LOOP;

return NULL;
END;
'
LANGUAGE plpgsql;

create trigger logchange2 AFTER UPDATE on TABLENAME FOR EACH ROW EXECUTE
PROCEDURE logchange2();