package Derived;

use strict;
use warnings;

use base 'Base';
use fields qw( _f );

sub new
{
    my $class = shift;
    my Derived $self = fields::new( $class );
    $self->SUPER::new();
    $self->{_f} = 'derived';
    return $self;
}

sub derived { my Derived $self = shift; $self->{_f}; }

1;