public function admin_register_meta_box_attributes()
{
$meta_box = new MetaBox('attributes', __('Attributes', 'wpk15'));
$meta_box->add_field('price', __('Price', 'wpk15'), function () {
$field = new Number();
$field->set_min(0.0);
return $field;
});
$meta_box->add_field('in-stock', __('In Stock', 'wpk15'), 'Checkbox');
$meta_box->add_post_type($this->_post_type_product);
}
