void register_compiler_function string name mixed impl bool cacheable Use this to dynamically register a compiler function plugin. Pass in the compiler function name, followed by the PHP function that implements it. The php-function callback impl can be either (a) a string containing the function name or (b) an array of the form array(&$object, $method) with &$object being a reference to an object and $method being a string containing the mehod-name or (c) an array of the form array(&$class, $method) with $class being a classname and $method being a class method of that class. $cacheable can be omitted in most cases. See Controlling Cacheability of Plugins' Output on how to it properly.