I'm using php.ini-optimized with register_globals = Off, so I access session variables
using $HTTP_SESSION_VARS["blah"].  This is defined as an array of objects.  I'm able
to access properties such as $HTTP_SESSION_VARS["blah"][0]->property, but I
can't run methods by doing $HTTP_SESSION_VARS["blah"][0]->method().  The
following test script illustrates the problem, reloading the page should increase the array size
of "blah" each time.  I found that I could work around the problem by copying the
session variable to a local variable, doing the methods on that, and then copying back.  I
compiled PHP as a dynamic DSO module using:

./configure --with-mysql --with-apxs=/usr/local/apache/bin/apxs

Here is the test script:

/* reload the page to increase the array size of "blah" */
class Test {
   var $item;
   function run() {
      $this->item = 1234;
   }
}

session_start();
session_register("blah");
if (!isset($HTTP_SESSION_VARS["blah"])) {
   $HTTP_SESSION_VARS["blah"] = array();
}

echo "array size before =
",sizeof($HTTP_SESSION_VARS["blah"]),"<br>n";
$S = sizeof($HTTP_SESSION_VARS["blah"]);
$HTTP_SESSION_VARS["blah"][$S] = new Test;

/** this doesn't work *******************/
// $HTTP_SESSION_VARS["blah"][$S]->run();
/****************************************/

/** this works **************************/
$SESSION = $HTTP_SESSION_VARS;
$SESSION["blah"][$S]->run();
$HTTP_SESSION_VARS = $SESSION;
/****************************************/

echo "array size after =
",sizeof($HTTP_SESSION_VARS["blah"]),"<br>n";

PLEASE NOTE:
------------
Ok, some comments on the above test code, it turns out I had a typo, so my "workaround" doesn't work.  Specifically, the line

$HTTP_SESSION_VARS = $SESSION;

was accidentally typed as

$HTTP_SESISON_VARS = $SESSION;

So the reason it worked is because the local $SESSION variable was being edited but it never got copied back to the session.  So restating the problems I'm seeing:

Objects inside arrays don't seem to work correctly in sessions.  The devshed.com site has some comments about this which say that maybe objects in arrays aren't properly deserialized in PHP 4.0.3 and 4.0.3pl1.  The relevant url is at

http://www.devshed.com/Server_Side/PHP/Commerce3/comments.html

It does not help to copy the entire session variable to a local variable.  However, I have some more test results for the test code shown above, in particular:

/** this does not work ******************/
$SESSION = $HTTP_SESSION_VARS["blah"];
$SESSION[$S]->run();
$HTTP_SESSION_VARS["blah"] = $SESSION;
/****************************************/

/** this works **************************/
$SESSION = $HTTP_SESSION_VARS["blah"][$S];
$SESSION->run();
$HTTP_SESSION_VARS["blah"][$S] = $SESSION;
/****************************************/

So if you copy the object itself, which is inside an array, to a local variable and execute the method there, you can copy back the result and the page seems to update properly when you reload.

umh, in order to test this... well - PHP crashes on win32
and it does not work on Linux (did not check if segfaults)

very strange, does not seem to have sth to do with
serialization, slightly modified script - the 4th line
crashes and the 5th does not, while both should be
completely equal (direct copy)

$SESSION = $HTTP_SESSION_VARS;
echo method_exists($SESSION["blah"][$S],'run');
echo method_exists($SESSION["blah"][$S],'run');
$SESSION["blah"][$S]->run();
// this line crashes
$HTTP_SESSION_VARS["blah"][$S]->run();
// this does not
$HTTP_SESSION_VARS = $SESSION;

Should be fixed in CVS. Please try latest snapshot from
http://snaps.php.net/ and reopen this bug report if
this doesn't work with it.

--Jani