## this starts like damian's example:

# Rational helper class...

package Astro::Data::Scientific;

use base Solar::Data;
use base Lunar::Data;

# <define methods here>



# "Differently rational" helper class...

package Astro::Data::Mythological;

use base Astrological::Data;        # Pre-empt normal methods
use base Astro::Data::Scientific;

# <overload any methods here that the 
#  heavens dictate should behave differently>



# Delegating class

package Astro::Data;

sub new {
    my $class = shift;
    my $sun_rises_in_west = @_ ? shift : $default_sun_rises_in_west;

    my $delegate = ("Astro::Data::" . ($sun_rises_in_west ? "Mythological" : "Scientific"))->new;

    bless {
        delegate => $delegate,
    }, $class;
}

# define like this or use Class::Accessor
sub sunrise_delegate {
    $_[0]{delegate};
}

# define like this or use Class::Delegation
sub get_sunrise_time {
    my $self = shift;

    $self->sunrise_delegate->get_sunrise_time(@_);
}