Q:

Drupal autocomplete, callback with multiple parameters

I am adding some autocomplete on a form alter. The problem is that in the callback, only the string in the textfield The autocomplete is on, is available. I also want to access a value from another textfield in the callback. How is this possible ?
/**
 * Implements hook_form_alter().
 */
function webform_conversion_jquery_form_webform_client_form_1_alter(&$form, &$form_state, $form_id) {
          //Load some extra function to process data
        module_load_include('inc', 'webform_conversion_jquery', '/includes/dataqueries');

        //Add extra js files
        drupal_add_js(drupal_get_path('module', 'webform_conversion_jquery') . '/js/conversionform.js');
        $form['submitted']['correspondentadress']['cor_street']['#autocomplete_path'] = 'conversionform/conversion_street';
    }
}

/**
 * Implements hook_menu().
 */
function webform_conversion_jquery_menu() {
    $items = array();

    $items['conversionform/conversion_street'] = array(
        'title' => 'Conversion street autocomplete',
        'page callback' => 'conversion_street_autocomplete',
        'access callback' => 'user_access',
        'access arguments' => array('access content'),
        'type' => MENU_CALLBACK,
    );

    return $items;
}

/**
 * Retrieve a JSON object containing autocomplete suggestions for streets depending on the zipcode.
 */
function conversion_street_autocomplete($street = '') {
    $street = "%" . $street . "%";
    $matches = array();
    $result = db_select('conversion_adresslist')
                    ->fields('conversion_adresslist', array('street'))
                    ->condition('street', $street, 'like')
                    ->execute();
    foreach ($result as $street) {
        $matches[$street->street] = $street->street;
    }
    drupal_json_output($matches);
}

I just want to be able to post extra information in the function:
conversion_street_autocomplete($street = '', $extraparameter)

A:

Ok, for as far as I can see it is not possible. maybe you can roll your own with the ajax functionality in fapi http://api.drupal.org/api/drupal/developer--topics--forms_api_reference.html/7#ajax
For now I solved it by implementing jquery.ui.autocomplete which is included in drupal 7

