public function _callExternalMethod(Smarty_Internal_Data $data, $name, $args)
    {
        /* @var Smarty $data ->smarty */
        $smarty = isset($data->smarty) ? $data->smarty : $data;
        if (!isset($smarty->ext->$name)) {
            $class = 'Smarty_Internal_Method_' . ucfirst($name);
            if (preg_match('/^(set|get)([A-Z].*)$/', $name, $match)) {
                if (!isset($this->_property_info[$prop = $match[2]])) {
                    // convert camel case to underscored name
                    $this->resolvedProperties[$prop] = $pn = strtolower(join('_',
                                                                             preg_split('/([A-Z][^A-Z]*)/', $prop, - 1,
                                                                                        PREG_SPLIT_NO_EMPTY |
                                                                                        PREG_SPLIT_DELIM_CAPTURE)));
                    $this->_property_info[$prop] = property_exists($data, $pn) ? 1 :
                        ($data->_objType == 2 && property_exists($smarty, $pn) ? 2 : 0);
                }
                if ($this->_property_info[$prop]) {
                    $pn = $this->resolvedProperties[$prop];
                    if ($match[1] == 'get') {
                        return $this->_property_info[$prop] == 1 ? $data->$pn : $data->smarty->$pn;
                    } else {
                        return $this->_property_info[$prop] == 1 ? $data->$pn = $args[0] :
                            $data->smarty->$pn = $args[0];
                    }
                } elseif (!class_exists($class)) {
                    throw new SmartyException("property '$pn' does not exist.");
                }
            }
            if (class_exists($class)) {
                $callback = array($smarty->ext->$name = new $class(), $name);
            }
        } else {
            $callback = array($smarty->ext->$name, $name);
        }
        array_unshift($args, $data);
        if (isset($callback) && $callback[0]->objMap | $data->_objType) {
            return call_user_func_array($callback, $args);
        }
        return call_user_func_array(array(new Smarty_Internal_Undefined(), $name), $args);
    }