php类中引用smarty的有关问题?

template_dir = Y_APP.DS.'view';//设置模版目录
$smarty->compile_dir = Y_CACHE.DS."view_c";//设置编译目录
$smarty->config_dir = Y_APP.DS.'config'.DS.'smarty';//配置目录变量
//$smarty->php_handling = SMARTY_PHP_ALLOW; //不赞成设置为SMARTY_PHP_ALLOW
$smarty->left_delimiter = "{";
$smarty->right_delimiter = "}";

//compile
#$smarty->compile_check = false;//编译检查变量

//Cache
$smarty->caching = true; //缓存模版的

 public function assign($tpl_var, $value = null, $nocache = false)
    {
        if (is_array($tpl_var)) {
            foreach ($tpl_var as $_key => $_val) {
                if ($_key != '') {
                    $this->tpl_vars[$_key] = new Smarty_variable($_val, $nocache);
                }
            }
        } else {
            if ($tpl_var != '') {
                $this->tpl_vars[$tpl_var] = new Smarty_variable($value, $nocache);
            }
        }
    }