Re: User defined exceptions

Hello all!
Trying to emulate "named" user defined exception with:
CREATE OR REPLACE FUNCTION exception_aaa ()  RETURNS text AS $body$
BEGIN
   return 31234;     
END;
$body$
LANGUAGE PLPGSQL
SECURITY DEFINER
;

do $$
begin
   raise exception using errcode=exception_aaa();
exception
   when  sqlstate exception_aaa()
   then
      raise notice 'got exception %',sqlstate;
end;
$$
 
Got:

ERROR:  syntax error at or near "exception_aaa"
LINE 20: sqlstate exception_aaa()

I looks like "when  sqlstate exception_aaa()" doesn't work.

How can I catch exception in this case?