Functions Returning Record Datatype

Hi,

 

I was wondering if I have a function that returns a record datatype, and I call it using the as keyword to specify the table structure, can I return a different structure than the one specified?

 

Say I call  select * from xy ('abc', 'def') as (samplea char,  sampleb char) for a function of

 

CREATE FUNCTION xy(char, char) RETURNS record AS'

Declare

testout record;

if userallowed = 0 then

 

else

    for testout in ''select * from testtable'' loop

          return next testout;

    end loop;

end if;

return null;

end;'

 language 'plpgsql';

 

Can I instead send back "errordescription text, errornumber int, errornext int"? How do I do that? 

 

I have a web front end and I have to get custom database errors to the front end. Maybe there is something more simple?