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If you are using sessions and use session_register()  to register objects, these objects are serialized automatically at the end of each PHP page, and are unserialized automatically on each of the following pages. This basically means that these objects can show up on any of your pages once they become part of your session.

You don’t need to serialize an object before adding it to a session var

example:

<?php include("class.exmaple.php");
$obj = new exampel ();
$_SESSION['obj']=$obj;?>

and to resume the object:

<?php include("class.example.php");
$obj = $_SESSION['obj']); ?>

<?php
$dirName = 'images';
$dir = opendir($dirName);
while ($filename = readdir($dir)) {
  echo $filename . '<br />';
}
closedir($dir);?>


Please note that if you use a “|” sign in a variable name your entire session will be cleared, so the example below will clear out all the contents of your session.

<?php
session_start();
$_SESSION["foo|bar"] = "foo";
?>

According to this bugreport this behaviour is intended. http://bugs.php.net/bug.php?id=33786

<?php
// Use of session_register() is deprecated
$hello = "Hello world!";
session_register("hello");

// The old way was to use $HTTP_SESSION_VARS
$HTTP_SESSION_VARS["message"] = "Hello world.";
?>

If session_start() was not called before this function is called, an implicit call to session_start() with no parameters will be made. $_SESSION does not mimic this behavior and requires session_start() before use.

POSTSCRIPT arrays, strings, and dictionaries are examples of composite objects. These objects have values that are separate from the object itself. That is, the character codes making up a string are stored in a different location in a POSTSCRIPT machine than the string object that POSTSCRIPT directly manipulates. Note that composite objects can share values. A dup operation on a string duplicates the object, but not its value. The duplicate object looks to the same place in the machine’s memory for its value.

When an array is created with a line such as

[1 2 3 (O’Leary)]

the square brackets play a more active role than is immediately evident. The left bracket is a POSTSCRIPT operator that leaves an object called a mark on the stack.
As the interpreter continues through the program line, it puts more objects on the stack until it encounters a right bracket, which is an operator that creates an array containing the stack contents back to the topmost mark. The mark is dropped from the stack and the array remains.

PostScript arrays are one-dimensional collections of objects. These objects are numbered from zero, so that a ten-item array is numbered from zero to nine. POSTSCRIPT arrays are different from those in other languages in that their elements need not all be of the same type. That is, a single array may contain, for example, strings, integers, dictionaries, and other arrays. An array in a program is denoted by any collection of PostScript objects surrounded by square brackets. Thus, the lines

[16 (twelve) 8]
[(sum) 6 14 add]

both set up arrays. The first has three members: two numbers and a string. The second array has two items in it: the string sum and the number 20. (Note that operators within an array definition are carried out as the array is being defined.) Arrays may also be defined by the array operator. This operator takes a number from the stack and constructs an array of that length. The line

10 array

would leave a ten-place array on the stack. The elements of this array are initially all POSTSCRIPT null objects.