package My::Parent;
use warnings;
use strict;

sub import {
    my $name = { short => 'frob',
                 long  => 'frobnicate'
             }->{ $_[1] };
    no strict 'refs';
    *{$name} = *_frobnicate;
}

sub new { bless $_[1], $_[0] }

sub _frobnicate { $_[0]{a} + $_[0]{b} }

__PACKAGE__