I'm building e-commerce web page with multiple sellers and buyers. After enabling the marketplace mp_product module I've noticed the following warning:
Warning: Call-time pass-by-reference has been deprecated; If you would like to pass it by reference, modify the declaration of module_invoke_all(). If you would like to enable call-time pass-by-reference, you can set allow_call_time_pass_reference to true in your INI file in .../drupal/modules/ubercart/ubercart_marketplace/mp_products/mp_products.module on line 219
Diving in to the code I've seen that there is a function call in which the variable is called by reference.
line 219 from mp_products.module is:
module_invoke_all('list_product', &$node);
This is happening because the php.ini variable "allow_call_time_pass_reference = Off". That's the recommended value so I didn't want to change it.
After a little googling I've seen that this is a bad PHP practice.
Here is a link from sitepoint.com describing the issue and presenting a solution:
http://www.sitepoint.com/article/object-oriented-php/7/
Instead of calling the function with the variable passed by reference, the function should be written to accept variables by reference.
I wanted to create a patch but I couldn't find the declaration of module_invoke_all. I'm new to drupal development 
My environment is:
Apache 2.2.8
PHP 5.2.6
MySQL 5.0.51b
Drupal 5.10
Ubercart 1.4
How can I fix this issue? I don't want to set allow_call_time_pass_reference = On
CHEERS, Jovan
