I am using module Mixpanel in my site. And I want to override function of this module. Here is link where we can see the function or code which I need to alter CODE NEED TO MODIFIED

Below is the code line which suggest that I can override this function :

    // Let other modules alter the defaults.
    drupal_alter('mixpanel_defaults', $properties, $account);

So from above line I am trying to override it with code as below, please let me know what I am doing wrong as it does not make any changes. However if I do same thing in main module it make changes but I don't want to make change in module but want to do in my custom module.

My custom module name: custom

function custom_mixpanel_defaults_alter($properties, $account) {

  $properties['distinct_id'] = $account->name;


When i see in system table weight of my custom module is 1000 and weight of Mixpanel is 0.

Please suggest! Thanks

  • 2
    Alter functions takes the variables as references. Try using &$properties instead of just $properties, and &$account in place of $account.
    – AjitS
    Dec 7, 2015 at 7:03
  • Thank you. as per your suggestion it worked :) I think you can post it as answer if you want to so that it can help other users as well.
    – jas
    Dec 7, 2015 at 7:06

1 Answer 1


The error is how you define the parameters, which should be defined as custom_mixpanel_defaults_alter(&$properties, $account).
PHP 5 automatically passes by reference any object passed to a function, but not the arrays. Since $properties is an array, you need to make the reference explicit.

Generally speaking, when you see a call to drupal_alter() like drupal_alter('node_view', $build), and you need to implement that alter hook, check the second and third parameter are object or arrays; in the case they are array, you need to explicitly declare the parameter as reference. In this case, hook_node_view_alter() is defined as hook_node_view_alter(&$build).

  • Thanks for explanation! and so it means we do not need to pass $account as reference &$account as its not array ?
    – jas
    Dec 7, 2015 at 7:13
  • Exactly: $account is an object, so PHP 5 will automatically pass it as reference.
    – apaderno
    Dec 7, 2015 at 7:41

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