Extending form validation functions

Question

How do I pass additional values to #element_validate so they can be used for validation?

I'm using hook_form_alter() and Drupal 7.

//Example 1
function my_validation_function($form, &$form_state) {
    //Validation Code
}

I would like to use:

//Example 2
function my_validation_function($form, &$form_state, $additional_values) {
    //Validation Code with access to $additional_values
}

This works for example 1:

$form['field']['#element_validate'] = array('my_validation_function');

How do I pass $additional_values to example 2 using $form['field']['#element_validate']

Answer 1

function where_ever_extra_data_originates_from() {
  $extra_data_to_pass_on_stored_here = &drupal_static(__FUNCTION__);
  $extra_data_to_pass_on_stored_here = $actual_extra_data
}

function my_validation_function($form, &$form_state) {
  //Here's our extra stuff now
  $extra_data = &drupal_static(where_ever_extra_data_originates_from);
}

Answer 2

You can add whatever extra elements to the $form_state array in your alter function and read them out in the validate function, like so:

function my_form_alter(&$form, &$form_state, $form_id) { 
  $form_state['additional_value'] = 'the extra value';
  $form['#validate'][] = 'my_validation_function';
}

function my_validation_function($form, &$form_state) {
  //Validation Code
  $extra = $form_state['additional_value']
}

Answer 3

You can't alter(add to) the number of parameters that are passed to a hook function. You could declare the variable that you want passed into the function as "global" -> Variable scope when you define it and again in the function which would give you access to the value.