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Unexpected "silent" type-cast with initialized but un-set members

php.internals

Morten Fangel

20 years ago

Hi,

Look at the following example:
---
<?php
class Foo {
public $bar;
function __construct() {
$this->bar->baz = 'blah';
}
}
$foo = new Foo();
print_r($foo);
?>

--

It results in:
---
Foo Object
(
[bar] => stdClass Object
(
[baz] => blah
)
)
---

Foo->bar is never declared as anything but "public" and is therefor
"type-less" (is there a proper term for this?).
As soon as I try to assign Foo->bar->baz, then Foo->bar is cast to an
stdObject and the baz property is set.

This is pretty much what you would expect, but IMHO this should generate an
E_NOTICE because you are using a non-object as an object..

Is this just my opinion?

Morten Fangel // fangel

Antony Dovgal

20 years ago

On 16.02.2006 14:32, Morten Fangel wrote:

> Hi,
>
> Look at the following example:
> ---
> <?php
> class Foo {
>   public $bar;
>   function __construct() {
>     $this->bar->baz = 'blah';
>   }
> }
> $foo = new Foo();
> print_r($foo);
> ?>
> --
>
> It results in:
> ---
> Foo Object
> (
>     [bar] => stdClass Object
>         (
>             [baz] => blah
>         )
> )
> ---

<?php
$a->bar = 1;
var_dump($a);
?>
This code is much simpler, huh?

--
Wbr,
Antony Dovgal

Morten Fangel

20 years ago

On Thursday 16 February 2006 12:39, Antony Dovgal wrote:

> <?php
> $a->bar = 1;
> var_dump($a);
> ?>
> This code is much simpler, huh?

Yeah, I must have been blinded by the lights. It merely resembles
$foo['bar'] = 'baz';
Where $foo is cast as an array without the need to do $foo = array(); first.

So I guess there is no need for a notice when you apply the same "pattern" to
an object.

Wow - what a great debut on the internals list, huh? ;)

Morten

Jochem Maas

20 years ago

Morten Fangel wrote:

> On Thursday 16 February 2006 12:39, Antony Dovgal wrote:
>
>><?php
>>$a->bar = 1;
>>var_dump($a);
>>?>
>>This code is much simpler, huh?
>
> Yeah, I must have been blinded by the lights. It merely resembles
> $foo['bar'] = 'baz';
> Where $foo is cast as an array without the need to do $foo = array(); first.
>
> So I guess there is no need for a notice when you apply the same "pattern" to
> an object.

if that is the logic being applied in the engine then one might to wonder why a
function such as array_merge() was changed to emit a warning when any of
it's arguments are not arrays (whereas sometime in the past it used to swallow
[and I assume 'autocast'] whatever it was given without a hiccup).

I have been told that such warnings as array_merge() now emits are for my own
good (in not so many words I was told it was "to protect me from my stupid self"),
if it's good for me when I use array_merge() why not when an object is created
implicitly (as in the example above)? actually my preference would be to drop the warning
in array_merge() in this case (it seems like a more php way of doing things, imo)

<!--

unset($a); $a->i = 1; 				// this is not a problem
$b = 1; $c = 2; $d = array_merge($b, $c);	// but this is bad programming?

-->

I'm very interested to learn what people think about this kind of thing in general -
and obviously if someone knows of material that explains the reasoning behind the
percieved inconsistency/problem I'd be very grateful.

tar,
jochem

Morten Fangel

20 years ago

On Thursday 16 February 2006 13:45, Jochem Maas wrote:

> if that is the logic being applied in the engine then one might to wonder
> why a function such as array_merge() was changed to emit a warning when any
> of it's arguments are not arrays (whereas sometime in the past it used to
> swallow [and I assume 'autocast'] whatever it was given without a hiccup).
>
> I have been told that such warnings as array_merge() now emits are for my
> own good (in not so many words I was told it was "to protect me from my
> stupid self"), if it's good for me when I use array_merge() why not when an
> object is created implicitly (as in the example above)? actually my
> preference would be to drop the warning in array_merge() in this case (it
> seems like a more php way of doing things, imo)
>
> <!--
>
> unset($a); $a->i = 1; 				// this is not a problem
> $b = 1; $c = 2; $d = array_merge($b, $c);	// but this is bad programming?
>
> -->

This was my initial thought when I saw the behaviour: "wow - this just wants
you to do some _lousy_ programmering" and therefor thought that it needed a
E_NOTICE.. (which I still do, but now I understand why it currently don't do
so)

If some functions throws notices when they have to "autocast", why doesn't php
always do this (throws notices)? Or maybe it should just throw E_STRICT and
let the perfectionists remove those issues if they want to do so...

>
> I'm very interested to learn what people think about this kind of thing in
> general - and obviously if someone knows of material that explains the
> reasoning behind the percieved inconsistency/problem I'd be very grateful.
>
> tar,
> jochem

Regards
Morten