package Your::Class;
our $VERSION= 1.001_001;

package Your::Class::_Implementation;

BEGIN {
    require constant;
    my $offset= 0;
    for my $member ( qw<
        _NAME _ADDRESS _PHONE ...
    > ) {
        constant->import( $member, $offset++ );
    }
}

sub Your::Class::new {
    ...
    $self->[_NAME]= ...;
}