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Date: Mon, 28 Jan 2008 17:49:26 +0100
Reply-To: Marcus Boerger <helly@php.net>
Message-ID: <868592137.20080128174926@marcus-boerger.de>
To: "Robin Fernandes" <rewbs.soal@gmail.com>
CC: "Marcus Boerger" <helly@php.net>, internals@lists.php.net, robin@soal.org
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References: <5a8807d10801280520u7f8c7a9o8d2ab2efaa9c7644@mail.gmail.com> <1109819085.20080128151237@marcus-boerger.de> <5a8807d10801280718p6d52f689s3a13c4d8c6521a3f@mail.gmail.com>
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Subject: Re: [PHP-DEV] Protected static props redeclared as public share value across classes
From: helly@php.net (Marcus Boerger)

Hello Robin,

  I checked it out in more detail and it is indeed broken as in it is not
consistent:
[marcus@zaphod PHP_5_3]$ php -r 'class A { protected static $p=1; } class B extends A { protected static $p=2; } ReflectionClass::Export("B");'
-> works == 2 properties
-> but should fail because of changed value

[marcus@zaphod PHP_5_3]$ php -r 'class A { protected static $p=1; } class B extends A { public static $p=2; } ReflectionClass::Export("B");'
Fatal error: Cannot change initial value of property static protected A::$p in class B in Command line code on line 1

[marcus@zaphod PHP_5_3]$ php -r 'class A { public static $p=1; } class B extends A { protected static $p=2; } ReflectionClass::Export("B");'
Fatal error: Access level to B::$p must be public (as in class A) in Command line code on line 1

[marcus@zaphod PHP_5_3]$ php -r 'class A { public static $p=1; } class B extends A { public static $p=2; } ReflectionClass::Export("B");'
-> works == 2 properties
-> but should fail becasue of changed value

So we need to fix this.

marcus

Monday, January 28, 2008, 4:18:50 PM, you wrote:

> Hi Marcus,

> Thanks for the prompt reply and explanation. I have some further
> questions though:

>> If the base class had the property defined as private
>> then the property is private to that specific class and not directly
>> accessible by derived classes that is it's name gets prefixed with the class
>> name.. So in:
>> class A { private static $p; } class B extends A { private static $p; }
>> we have two different properties:

> Understood. But if we have two separate properties for the reason that
> A::$p is not visible to B, then how about these cases?
> class A { protected static $p; } class B extends A { protected static $p; }
> class A { public static $p; } class B extends A { public static $p; }

> In both of those cases, A::$p is visible to the derived class, but the
> re-declaration results in A::$p and B::$p being two separate
> properties (see pastebin.com/fca2cd5b and pastebin.com/f4f94b32d for a
> demonstration). This is one of the reasons I find the case where we
> end up with only one property value to be surprising.

> Another reason is that, as illustrated in my previous post, PHP's
> behaviour doesn't seem to correlate with the inheritance rules of
> other languages I'm familiar with: you always end up with two distinct
> static properties in Java, C++ and C# (though of course I understand
> this fact on its own is does not mean PHP is wrong :).

> Lastly, with overridden static methods, PHP always yields two distinct
> methods, regardless of the visibility modifiers. See
> http://pastebin.com/f27f009c4 . Granted, with methods any other
> behaviour would be very odd indeed, but it does emphasize an
> inconsistency between method and property inheritance rules in PHP.

> So for now I continue to feel this is a little strange. Any further
> explanations would be greatly appreciated. :)

> Thanks,
> Robin

>> Best regards,
>>  Marcus




Best regards,
 Marcus