Session language switcher prevents pages from being cached

subscribing.

-  // Request parameter.
+  // Request parameter: we need to update the session parameter only if we have
+  // an authenticated user.
   if (isset($_GET[$param]) && isset($languages[$langcode = $_GET[$param]])) {
-    return $_SESSION[$param] = $langcode;
+    global $user;
+    return $user->uid ? ($_SESSION[$param] = $langcode) : $langcode;
   }

Two inline assignments, that's at least two too many.

Otherwise, the fix is ok. And just proves that the session language switcher is really a bad idea.

Let's get this in.

People need to understand that serving different content at the same URL is just a bad idea. But that's out of the scope of this issue :)

Committed to CVS HEAD. Thanks.