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Date: Tue, 05 Jun 2007 17:57:51 +0200
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To: Jochem Maas <jochem@iamjochem.com>
CC: Bart de Boer <bart@mediawave.nl>,  internals@lists.php.net, 
 Ken Stanley <dohpaz@gmail.com>
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Subject: Re: [PHP-DEV] late static binding (please break BC?)
From: colder@php.net (Etienne Kneuss)

Jochem Maas wrote:
> Bart de Boer wrote:
>   
>> Ken Stanley wrote:
>>
>>     
>
> ...
>
>   
>> That's not right. Accessing the child class would only be possible from
>> within an instantiated object. Unlike parent::, you will never be able
>> to use static:: in a purely static context. Imagine there are multiple
>> child classes which all inherit from the same base class. If there's no
>> instance, PHP won't be able to know which child class to target with
>> child::, static:: or whateverkeyword:: since it can be any one of those
>> child classes.
>>     
>
> huh??? the 'child' class would refer to the class that was actually named
> when then call to the method was made (thats what late static binding means,
> does it not?):
>
> class Data {
> 	static function getTableName() {
> 		throw new Exception('WTF');
> 	}
>
> 	static function findRange() {
> 		$t = child::getTableName();
> 	}
> }
>
> class Prod {
> 	static function getTableName() {
> 		return 'PRODS';
> 	}	
> }
>
> Data::findRange(); // child = Data class
> Prod::findRange(); // child = Prod class
>
> if you require a class instance in order to use 'child' then
> the whole point is moot - because you can already do
>
> 	$child = get_class($this);
>
> inside the relevant function (assuming the function is not declared static,
> and why would you declare it as such if your requiring an instance to use 'child'?).
>
> maybe 'child' should be called 'callee' or even 'lsb' (that would make people
> hit the docs for sure :-)). alternatively maybe 'this' could be used as the LSB keyword:
>
> 	this::foo();
>
> the samentics for determining what class is referred to with 'this::' is akin to
> that used for determining what class is referred with '$this->', no?
>
> MAYBE php6 should do late static binding for 'self', akin to other OO oriented
> scripting langs .. and just live with BC. I seriously wonder whether much code would
> break ... given that 'self' is not currently late binding how often would people have actually
> overwritten static methods ion child classes that are being called via the 'self' syntax
> in [parent] classes?
>   
Hello,

In an instance, fetching the class and running call_user_func is quite 
overkill, hopefully the dynamic access of class method/member/const will 
get accepted/commited. There is no reason (implementation wise) to 
restrict LSB to static callstacks only.

By the way, "child" is not a good term either as it won't always 
represent the child, i.e. the class itself.

Changing the behavior of "self" seems like a bad idea, it will make 
every script using "self" (many) rely on the call stack, which will 
among other things break BC and slow things down.


-- 
Etienne Kneuss
http://www.colder.ch
colder@php.net

Men never do evil so completely and cheerfully as 
when they do it from a religious conviction.
-- Pascal