Unknown constant (ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL) in functions_prices.php

The function zen_get_attributes_price_factor in /includes/functions/functions_prices.php uses an unknown constant (highlighted):

////
// return attributes_price_factor
  function zen_get_attributes_price_factor($price, $special, $factor, $offset) {
    if (ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL =='1' and $special) {
      // calculate from specials_new_products_price
      $calculated_price = $special * ($factor - $offset);
    } else {
      // calculate from products_price
      $calculated_price = $price * ($factor - $offset);
    }
//    return '$price ' . $price . ' $special ' . $special . ' $factor ' . $factor . ' $offset ' . $offset;
    return $calculated_price;
  }

I've used the Developers Tool Kit to no avail; it's not defined in the database, either.

Yup, I cannot find it in the code (or database) for 1.5.1 either. It is however set in the 1.5.2 release candidate ("/includes/classes/shopping_cart.php"). Looks to be an "override" of sorts... Maybe it would be better to just to see if the constant is defined rather then checking the value? Or refactoring the function and related code? Maybe another will have some additional insight for us :)

There's an undefined constant (ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL), used in /includes/functions/functions_prices.php (ca. line 1024); it exists neither in language files nor in the database:

  function zen_get_attributes_price_factor($price, $special, $factor, $offset) {
    if (ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL =='1' and $special) {
      // calculate from specials_new_products_price
      $calculated_price = $special * ($factor - $offset);
    } else {
      // calculate from products_price
      $calculated_price = $price * ($factor - $offset);
    }
//    return '$price ' . $price . ' $special ' . $special . ' $factor ' . $factor . ' $offset ' . $offset;
    return $calculated_price;
  }

In the same file, there's also an uninitialized value in zen_get_attributes_price_final_onetime (line 1122); suggest changing

////
// attributes final price onetime
  function zen_get_attributes_price_final_onetime($attribute, $qty= 1, $pre_selected_onetime) {
    global $db;
    global $cart;

    if ($pre_selected_onetime == '' or $attribute != $pre_selected_onetime->fields["products_attributes_id"]) {
      $pre_selected_onetime = $db->Execute("select pa.* from " . TABLE_PRODUCTS_ATTRIBUTES . " pa where pa.products_attributes_id= '" . (int)$attribute . "'");
    } else {
      // use existing select
    }

// one time charges
    // onetime charge
      $attributes_price_final_onetime += $pre_selected_onetime->fields["attributes_price_onetime"];

    // price factor
    $display_normal_price = zen_get_products_actual_price($pre_selected_onetime->fields["products_id"]);
    $display_special_price = zen_get_products_special_price($pre_selected_onetime->fields["products_id"]);

to

////
// attributes final price onetime
  function zen_get_attributes_price_final_onetime($attribute, $qty= 1, $pre_selected_onetime) {
    global $db;
    global $cart;

    if ($pre_selected_onetime == '' or $attribute != $pre_selected_onetime->fields["products_attributes_id"]) {
      $pre_selected_onetime = $db->Execute("select pa.* from " . TABLE_PRODUCTS_ATTRIBUTES . " pa where pa.products_attributes_id= '" . (int)$attribute . "'");
    } else {
      // use existing select
    }

// one time charges
    // onetime charge
      $attributes_price_final_onetime = $pre_selected_onetime->fields["attributes_price_onetime"];

    // price factor
    $display_normal_price = zen_get_products_actual_price($pre_selected_onetime->fields["products_id"]);
    $display_special_price = zen_get_products_special_price($pre_selected_onetime->fields["products_id"]);

ZC155e
While doing a "Report All Errors" for some heads-up on potential future errors, I get this error flagged on a product page, nothing in cart, not logged in, php 7.1.8.

PHP Notice: Use of undefined constant ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL - assumed 'ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL' in .....\includes\functions\functions_prices.php on line 1024
So I find this thread.

ATTRIBUTES_PRICE_FACTOR_FROM_SPECIAL is defined on the fly in classes/shopping_cart, but evidently this is not soon enough in the process.