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Date: Sat, 20 Oct 2007 13:55:14 -0700
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Subject: Re: [PHP-DEV] Order of class resolution with namespaces and autoload
From: stas@zend.com (Stanislav Malyshev)

> ::Exception, because the class resolution order seems to look like this:
> 
> - does the class exist (_already defined_) in the current namespace?
> - does the class exist in the global (non-prefixed or "::") namespace?
> - then try autoload

That's exactly how it works, with the amendment that only internal 
classes are considered on step 2.

> What I think should happen is:
> 
> - does the class exist in the current namespace?
> - can the class be autoloaded with the current namespace?
> - does the class exist in the global scope
> - global autoload

If it worked this way, you couldn't easily use global classes and old 
applications would be much harder to convert to namespaces. We think 
that using global Exception is much more frequent than defining your own 
Exception - and in the latter case you have the choice to name it 
something that is not the same as existing class, while in the latter 
case you do not. So we decided to make resolution rules so that it makes 
easier to work with the most frequent case and makes easier to work with 
existing code.

> The other alternative would be to say that if you want to use a global 
> class inside a namespace you MUST prefix it with ::. I think this is 

We consider it not the best choice. Using of global classes is 
ubiquitous in current applications, always requiring :: would make it 
very hard to convert them to namespaced code. We think it would require 
much more work than just having "require_once" in places when you 
override the internal classes.

> reasonable since if you have a namespaced file it's already not going to 
> work with anything before PHP 5.3, and that would remove the two 

The problem is not working with PHP before 5.3, the problem is using 
code that was written before 5.3. We try to make this code as easy as 
possible to upgrade, and it seems that blocking access to internal 
classes would not do us much good.
-- 
Stanislav Malyshev, Zend Software Architect
stas@zend.com   http://www.zend.com/
(408)253-8829   MSN: stas@zend.com