Smarty 配置文件中的相对路径

<?php
//include_once("Smarty/libs/Smarty.class.php"); 
require_once $_SERVER['DOCUMENT_ROOT']."/Smarty/libs/Smarty.class.php";
$smarty=new smarty();  
$smarty->compile_check=true;
$smarty->config_dir=$_SERVER['DOCUMENT_ROOT']."Smarty/libs/Config_File.class.php"; 
$smarty->caching=false;    
$smarty->template_dir=$_SERVER['DOCUMENT_ROOT']."/Smarty/templates";  
$smarty->compile_dir=$_SERVER['DOCUMENT_ROOT']."/Smarty/templates_c";   
$smarty->cache_dir=$_SERVER['DOCUMENT_ROOT']."/Smarty/cache";  
//  --------------------------------------
$smarty->left_delimiter="<{";
$smarty->right_delimiter="}>";
?>