Assigned to the SPL maintainer.

The ArrayObject::STD_PROP_LIST doesn't seem to alter the behaviour of ArrayObject in any noticeable way. Setting properties on an instance of ArrayObject at runtime adds the properties to the instance, rather than storing them as key/value pairs in the internal array. $o->prop = val is a property with or without this flag and cannot be accessed via $o['prop']

It would seem ArrayObject::ARRAY_AS_PROPS is what turns properties into key/value pairs and allows you to access the key/value pairs as instance properties. $o->prop = val is the same as $o['prop'] = val.


<?php
error_reporting(-1);
$a = array('first' => 'a');

// Build objects
$o1 = new ArrayObject($a                                                          );
$o2 = new ArrayObject($a, ArrayObject::STD_PROP_LIST                              );
$o3 = new ArrayObject($a,                              ArrayObject::ARRAY_AS_PROPS);
$o4 = new ArrayObject($a, ArrayObject::STD_PROP_LIST | ArrayObject::ARRAY_AS_PROPS);

$ao = array($o1, $o2, $o3, $o4);

foreach($ao as $o) {
  // Add a property.
  $o->last = 'z';

  // Show flags, foreach() and properties.
  echo
    'Flags set to ', str_pad(decbin($o->getFlags()), 2, '0', STR_PAD_LEFT), PHP_EOL,
    print_r($o, True), PHP_EOL,
    'Foreach:', PHP_EOL;
  
  foreach($o as $k => $v) {
    echo "  $k => $v", PHP_EOL;
  }

  echo
    'Properties:', PHP_EOL,
    "  first => {$o->first}", PHP_EOL,
    "  last => {$o->last}", PHP_EOL,
    PHP_EOL;
}
?>

outputs (using 5.3+) ...


Flags set to 00
ArrayObject Object
(
    [last] => z
    [storage:ArrayObject:private] => Array
        (
            [first] => a
        )

)

Foreach:
  first => a
Properties:

Notice: Undefined property: ArrayObject::$first in Z:\ar1.php on line 29
  first =>
  last => z

Flags set to 01
ArrayObject Object
(
    [last] => z
    [storage:ArrayObject:private] => Array
        (
            [first] => a
        )

)

Foreach:
  first => a
Properties:

Notice: Undefined property: ArrayObject::$first in Z:\ar1.php on line 29
  first =>
  last => z

Flags set to 10
ArrayObject Object
(
    [storage:ArrayObject:private] => Array
        (
            [first] => a
            [last] => z
        )

)

Foreach:
  first => a
  last => z
Properties:
  first => a
  last => z

Flags set to 11
ArrayObject Object
(
    [storage:ArrayObject:private] => Array
        (
            [first] => a
            [last] => z
        )

)

Foreach:
  first => a
  last => z
Properties:
  first => a
  last => z

This is not a bug, as explained by rquadling at php dot net above.

But the later example proves that:
"The ArrayObject::STD_PROP_LIST doesn't seem to alter the behaviour of 
ArrayObject in any noticeable way"
so the PHP documentation is wrong ?

ArrayObject::STD_PROP_LIST seems to work in scattered versions of 5.3.x

I have confirmed it working for 5.3.21 but it does NOT work for 5.3.23 nor 5.3.15

By the way, how exactly isn't this a bug? Is it intentional for it to work in 
scattered versions of 5.3.x?

If so the documentation should reflect this