# Previous (manual OO) code:
sub error_mode {                                                                
    my ($s, $mode) = @_;                                                        
    if ($mode) {                                                                
        $s->_err('Invalid error_mode', $s->{error_mode})                        
            unless $mode =~ /^(carp|error|both)$/;                              
        $s->{error_mode} = $mode;                                               
    }                                                                           
                                                                                
    $s->{error_mode};                                                           
}