Re: Protected static props redeclared as public share value across classes

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