Form validation - callback function question

[eluser]CroNiX[/eluser]
Just pass the variable to the validation function.

Code:

$id = 'some_variable';
$this->form_validation->set_rules('field', 'Field', "required|callback_foo[$id]");

Code:

function foo($field_value, $params)
{
  //$params = 'some_variable';
}