$autoload_filters

If there are some filters that you wish to load on every template invocation, you can specify them using this variable and Smarty will automatically load them for you. The variable is an associative array where keys are filter types and values are arrays of the filter names. For example:

$smarty->autoload_filters = array('pre' => array('trim', 'stamp'),
                                  'output' => array('convert'));