Description:
------------
Calling serialize() on an object whose name is the same as the key under which it's saved in $_SESSION makes the object unusable (its methods can't be called.

If I store store a serialized version of the object under a key that's different from the name of the variable that points to the object, then everything works fine. If this is by design and must remain this way, I want to tell you that this is VERY counterintuitive and must be prominently documented.

I can reproduce this on a Linux server (with PHP 5.2.5 and 5.2.6) but not on Windows Vista.

Reproduce code:
---------------
<?php
	session_start();
	ob_start();

	class GoodObject {
		private $count = 0;
		public function doSmth()
		{
			echo "$this->count <br>";
			$this->count++;
		}
	}

	if(!isset($_SESSION['myObj'])) {
		$myObj = new GoodObject();
	}
	else {
		$s = $_SESSION['myObj'];
		$myObj = unserialize($s);
	}
	
	$myObj->doSmth();
	$s = serialize($myObj);
	$_SESSION['myObj'] = $s;
	$myObj->doSmth(); // this fails on the second page load
?>

Expected result:
----------------
Converting an object to a string should not change the object, and the last statement in this script should output the value of $count.

Actual result:
--------------
On the second load of the page, I get this:

Fatal error: Call to a member function doSmth() on a non-object in [path to the file] on line 26