$ perle ' use Scalar::Util "blessed"; for (1, 2) { say "Run: $_"; my $ret = foo(); my $err = blessed $ret; if (defined $err) { say qq{Error "$err" detected}; say qq{Code: $ret->[0]}; say qq{Errstr: $ret->[1]}; } else { say qq{Success!}; say for @$ret; } } sub foo { state $error = 0; my $retval; if ($error) { $retval = bless [0, "error was ..."] => "YouveGotError"; } else { $retval = [42, 43]; } $error ^= 1; return $retval; } ' Run: 1 Success! 42 43 Run: 2 Error "YouveGotError" detected Code: 0 Errstr: error was ...