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Date: Mon, 28 Jan 2008 18:02:54 +0100
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To: Marcus Boerger <helly@php.net>
CC: Robin Fernandes <rewbs.soal@gmail.com>, internals@lists.php.net, 
 robin@soal.org
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Subject: Re: [PHP-DEV] Protected static props redeclared as public share value
 across classes
From: jochem@iamjochem.com (Jochem Maas)

Marcus Boerger schreef:
> 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.

I don't get the 'but should fail because of changed value' - isn't the changed value akin
to overloading a method - where the body of the method changes (obviously)?

I also surmise that the issue becomes more tricky if you consider late static binding,
which I am assuming is still scheduled for php6, and as such it may be worth holding back
making a fix until it is clearer what the larger ramifications are?

> 
> 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
>