Use this to dynamically register prefilters to run templates through before they are compiled. See template prefilters for more information on how to setup a prefiltering function.
The php-function callback function can be either:
A string containing the function name
An array of the form array(&$object, $method) with &$object being a reference to an object and $method being a string containing the method-name
An array of the form array($class, $method) with $class being the class name and $method being a method of the class.
See also unregister_prefilter(), register_postfilter(), register_ouputfilter(), load_filter(), $autoload_filters and template output filters section.