Function returning record

Is it possible in PostgreSQL to write a function that would return a
record type.

What I need is something like this:

create function my_func(varchar)
return record as '
declare
my_rec record;
begin
select null as field1, null as field2
into my_rec;

.... some processing to populate the actual values of the record

return my_rec;
end;
' LANGUAGE 'plpgsql';

I get the following when I try to compile this:
NOTICE: ProcedureCreate: return type 'record' is only a shell

and following when I try to execute it (even though I am not sure how
to execute this at all);
ERROR: fmgr_info: function 0: cache lookup failed

Please help.

Thanks a lot in advance

Alla