if ( $obj->validate($q->param('new_userid')) ) {
   create_new_user( $q->param('new_userid'))
}
else {
   # tell the user why it was invalid and ask again
   send_reprompt(
     "UserID was not valid for the following reasons:"
     $obj->error
   );
}

##</code><code>##

eval { $obj->get_stuff_a() }; if ($@) { $obj->try_a_backup() }
eval { $obj->get_stuff_b() }; if ($@) { $obj->try_b_backup() }
eval { $obj->get_stuff_c() }; if ($@) { $obj->try_c_backup() }

##</code><code>##

$obj->get_stuff_a() || $obj->try_a_backup || die $obj->error;
$obj->get_stuff_b() || $obj->try_b_backup || die $obj->error;
$obj->get_stuff_c() || $obj->try_c_backup || die $obj->error;
my @err = $obj->error;
if (@err) {
   warn 'Had to use one or more backup sources because:'."\t\n"
       .join("\t\n", @err)."\n";
}