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HomeBackend DevelopmentPHP Tutorial require中使用绝对路径的有关问题:常量重定义,变量覆盖,重调用增加开销

require中使用绝对路径的问题:常量重定义,变量覆盖,重调用增加开销。
因为相对路径引用总出问题,Google了下参考使用绝对路径。
在绝对路径使用中先后尝试了三种方法。
1、定义PATH常量,复用PATH进行require操作。
这里,如果主页面requrie的子页面具有相同define PAHT常量,报错重复定义常量PATH。
2、定$path变量,如下面的代码,重定义变量导致值的覆盖,可能导致其他相关require路径错误。
临时的决绝办法时重置$path变量,就像下面那样,但这给人感觉很傻。。
3、不用define也不用变量定义path路径,直接每次require时都重新构造路径,如
require dirname(__FILE__).'file_name.php';
但这让人感觉很笨……而且重复调用dirname加大开销很无趣……但是在不行就这样了,至少不会出错。
4、其他没有了,怎样更好的处理绝对路径的require,向各位讨教了。

PHP code
<!--

Code highlighting produced by Actipro CodeHighlighter (freeware)
http://www.CodeHighlighter.com/

-->
<?php #file:index.php,访问该页
$path = dirname(__FILE__);
require_once $path. '/../includes/pub_page_template.inc.php';
$path = dirname(__FILE__); //如果取消,下面的require错误。
require_once $path. '/../includes/conn.inc.php';
require_once $path. '/createdb.inc.php';
?>

<?php #file:pub_page_template.inc.php
$path = dirname(__FILE__);
require_once $path.  '/header.inc.php';
require_once $path. '/footer.inc.php';
?>



------解决方案--------------------
统一一下规则。指定义一个path常量不就可以了。
要不就用defined 做判断。如果定义了就不再定义了
------解决方案--------------------
定义PATH常量,这通常用于单一入口的应用
由于入口程序总是被首先运行,所以在这里定义就不会有问题

对于多入口的应用,PATH常量多定义于公共环境设置文件中(比如config.php)
为防止多次加载时出现问题,一般需要判断一下

if(defined('PATH')) return;
define('PATH', dirname(__FILE__));
//加载其他文件或定义公共类和函数的代码

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