sub setup_table {
    my ($self, $class) = @_;
    $class->load_components(qw/Core/);
    $class->table($self->tablename);

    my ($left_class, $right_class) = ($self->left_class, $self->right_class);
    my ($left_name, $right_name) = ($self->left_name, $self->right_name);

    my $l_info = $left_class->column_info($left_class->primary_columns);
    my $r_info = $right_class->column_info($right_class->primary_columns);

    $class->add_columns(
        $left_name  => { %$l_info, is_nullable => 0, },
        $right_name => { %$r_info, is_nullable => 0, },
    );
    $class->set_primary_key($left_name, $right_name);

    # us -> them
    $class->belongs_to( $left_name  => $left_class  );
    $class->belongs_to( $right_name => $right_class );

    # them -> us
    my $lmap = $self->left_to_map_relation;
    my $rmap = $self->right_to_map_relation;
    $left_class->has_many(  $lmap => $class, $left_name  );
    $right_class->has_many( $rmap => $class, $right_name );

    # many2many
    my $rights_from_left = $self->rights_from_left;
    my $lefts_from_right = $self->lefts_from_right;

    $left_class->many_to_many( $rights_from_left  => $lmap => $right_name )
      unless $self->suppress_left_m2m;

    $right_class->many_to_many( $lefts_from_right => $rmap => $left_name  )
      unless $self->suppress_right_m2m;
}