Internal casting of objects as array keys View as Markdown

Andi, any interest in this?

"Aidan Lister" aidan@php.net wrote in message
news:20040525143059.95129.qmail@pb1.pair.com...

Hi Andi,

Okay, it's not as simple as I thought it was - and you're correct, the
behaviour has not changed for php4/5.

Objects in both PHP4 and PHP5 will throw an error if you use the method
$blah[$someobject] = 'val'; (first method)
Warning: Illegal offset type

However, both do not throw an error if you use $blah = array($someobject
=>
'val'); (second method)

When we compare this behaviour with resources, it gets interesting. A
resource is casted to an interger when used as an array key for the first
method, but not the second.

This raises a number of questions:

1. Should the behaviour of method 1, and method 2 be the same.
2. Should the behaviour of objects be the same as resources (in the
   context
   of casting for use as an array key)

Below is a sample script which shows the differences

---

<pre> &lt;?php // Create a sample object class id_obj { var $_id; function id_obj($id) { $this->_id = $id; } } // Create two new objects $id1 = new id_obj(1); $id2 = new id_obj(2); // Add them to an array with two different methods $array = array(); $array[$id1] = 'sdf'; $array2 = array ($id1 => 'id1', $id2 => 'id2'); echo "objects: first method:\n"; var_dump($array); echo "objects: second method:\n"; var_dump($array2); // Create two resources $fp1 = fsockopen("www.example.com", 80, $errno, $errstr, 30); $fp2 = fsockopen("www.example.com", 80, $errno, $errstr, 30); // Add them to an array with two different methods $resarray = array(); $resarray[$fp1] = 'fp1'; $resarray2 = array($fp1 => 'fp1', $fp2 => 'fp2'); // Show the result echo "resources: first method:\n"; var_dump($resarray); echo "resources: second method:\n"; var_dump($resarray2); ?> </pre>

---

The output:

---

Warning: Illegal offset type on line 9
objects: first method:
array(0) {
}
objects: second method:
array(0) {
}
resources: first method:
array(1) {
[2]=>
string(3) "fp1"
}
resources: second method:
array(0) {
}

Thanks.

"Andi Gutmans" andi@zend.com wrote in message
news:5.1.0.14.2.20040525161238.061c8f78@127.0.0.1...

This code doesn't seem to have changed. Can you send me a 3-4 liner
which
errors out in PHP 4 and not in PHP 4?

Thanks,

Andi

At 11:03 PM 5/25/2004 +1000, Aidan Lister wrote:

I'm going to go ahead and post this as a bug, unless there is a reason
noone
replied...

"Aidan Lister" aidan@php.net wrote in message
news:20040522064028.3397.qmail@pb1.pair.com...

Hello devs,

I'd like to discuss the use of objects as array keys.

<?php
class idobject {
private $_id;
function __construct ($id) { $this->_id = $id; }
function __tostring () { return (int)$this->_id; }
}

$blah1 = new idobject(1);
$blah2 = new idobject(2);
$blah3 = new idobject(3);
$blah4 = new idobject(4);

$array = array (
$blah1 => 'blah1',
$blah2 => 'blah2',
$blah3 => 'blah3',
$blah4 => 'blah4',
);

echo "<pre>";
var_dump($array);
echo "</pre>";
?>

In PHP4 this results in an error,
In PHP5 there is no error, the array is simply empty.

An array key can only be a string/int, thus, when someone attempts
to
use
an
array as a key would it not make sense to cast the object?

This behaviour would then be consistant with resources.

Regards,
Aidan