An object SplDoublyLinkedList () the same situation.

HACK:

<?php

class HackStack extends \SplStack
{
    private $_data;
    
    public function __sleep()
    {
        $this->_data = array();
        
        $this->rewind();
        
        while ($this->valid()) {
            $this->_data[] = $this->current();
            $this->next();
        }
        
        return array('_data');
    }
    
    public function __wakeup()
    {
        foreach ($this->_data as $row) {
            $this->push($row);
        }
        
        $this->_data = array ();
    }
}



$SHM_KEY = ftok(__FILE__, chr( 4 ) );
$data =  shm_attach($SHM_KEY, 102400, 0666);

$testData = array("hello","world","1","2","3");
$test = new HackStack();
$test->push($testData);
$test->push($testData);

echo "one: \n";
print_r($test);

shm_put_var($data, 1, $test);

echo "two: \n";
print_r(shm_get_var($data, 1));

shm_detach($data);
?>

RESULT:

one: 
HackStack Object
(
    [_data:HackStack:private] => 
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => Array
                (
                    [0] => hello
                    [1] => world
                    [2] => 1
                    [3] => 2
                    [4] => 3
                )

            [1] => Array
                (
                    [0] => hello
                    [1] => world
                    [2] => 1
                    [3] => 2
                    [4] => 3
                )

        )

)
two: 
HackStack Object
(
    [flags:SplDoublyLinkedList:private] => 6
    [dllist:SplDoublyLinkedList:private] => Array
        (
            [0] => Array
                (
                    [0] => hello
                    [1] => world
                    [2] => 1
                    [3] => 2
                    [4] => 3
                )

            [1] => Array
                (
                    [0] => hello
                    [1] => world
                    [2] => 1
                    [3] => 2
                    [4] => 3
                )

        )

)

The issue here is that the data is serialized. The docs on shm_put_var()currently state

    All variable-types  except resources are supported. 

Which is not correct as serialisation of objects from interal classes (PDO, DOM, SPL, ...) is often not possible for various reasons (representing C structures etc.)

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.