Class rewrite / extends and constant validity?

Question

I try to implement a module in which I need to rewrite Mage_Catalog_Model_Product_Option.

I then add the following file to the module

<?php
class Mine_Custoptiontype_Model_Catalog_Product_Option extends Mage_Catalog_Model_Product_Option
{
    const OPTION_GROUP_FILESSTATE       = 'filesstate';
    const OPTION_TYPE_FILESSTATE_TYPE   = 'filesstate_type';
    /**
     * Get group name of option by given option type
     *
     * @param string $type
     * @return string
     */
    public function getGroupByType($type = null)
    {
        if (is_null($type)) {
            $type = $this->getType();
        }

        $group = parent::getGroupByType($type);
        if( $group === '' && $type = self::OPTION_TYPE_FILESSTATE_TYPE ){
            $group = self::OPTION_GROUP_FILESSTATE;
        }
        return $group;

    }
    /**
     * Group model factory
     *
     * @param string $type Option type
     * @return Mage_Catalog_Model_Product_Option_Group_Abstract
     */
    public function groupFactory($type)
    {
        if( $type === self::OPTION_TYPE_FILESSTATE_TYPE ){
            return Mage::getModel('custoptiontype/catalog_product_option_type_filesstatetype');
        }
        return parent::groupFactory($type);
    }
}
?>

and modify my model config.xml file :

<models>
  <catalog>
    <rewrite>
      <product_option>Mine_Custoptiontype_Model_Catalog_Product_Option</product_option>
    </rewrite>
  </catalog>
</models> 

but when I would like to access the OPTION_GROUP_FILESSTATE and OPTION_TYPE_FILESSTATE_TYPE using app/code/core/Mage/Catalog/Model/Resource/Product/Option.php,

I have got errors saying these 2 constant do not exist…

Help me please !

Answer 1

You cannot access constants from a child class using the parent class name.
Those constants don't exist in Mage_Catalog_Model_Product_Option.
You should be able to access them like this:

Mine_Custoptiontype_Model_Catalog_Product_Option::OPTION_GROUP_FILESSTATE
Mine_Custoptiontype_Model_Catalog_Product_Option::OPTION_TYPE_FILESSTATE_TYPE