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