用于通过php提供css的php标头

Question

Here's the thing. I'm serving somewhat compressed CSS content

(`str_replace(array("", "
", "\t", '\s\s+'), '', cssGoesHere)`) 

via a PHP file in my page:

<link rel="stylesheet" type="text/css" href="/css/loader.css.php" />

The question is: how do I make the browser cache the css returned, BUT update the cache if the content is changed?

The PHP file is not being modified, so appending something like

<?php echo filemtime('/css/loader.css.php'); ?>

to the href attribute is not an option. Can this be solved with headers, and if so, how? Because AFAIK if I serve it like I wrote above, the browser will just cache the result and keep reusing the cache (provided, of course, the browser is enabled/capable of doing so), but I need it to know when the content is changed.

Edit: I've made a github project with my code (though I did change it alot for more flexibility since I wrote this). Here's the link: https://github.com/jurchiks/YACC
If you have any suggestions, write them to my e-mail or smth.

Answer 1

It can be solved by headers cache-control, BUT this have proved to be not very effective. Because some browser do overwrite or modify your forced settings.

I can't see where you getting the CSS data from, if it's a CSS file you could get the filemtime of the css file as version indicator or simply supply somewhere a version string which has to be changed each time the CSS file changes.

By the way, str_replace(array("", " ", "\t", '\s\s+'), does not effectively remove all newlines. Your should use something like

$foo = nl2br($string, FALSE);
$bar = str_replace(array('<br>', '\s\s+'), '', cssGoesHere)

instead.

HTH :)