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Date: Mon, 27 Aug 2007 10:49:22 -0700
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Subject: Re: [PHP-DEV] Namespaces and __autoload()
From: stas@zend.com (Stanislav Malyshev)

> <?php
> namespace Foo;
> throw new Exception;
> 
> In this case PHP first looks for Foo::Exception and only then for internal
> Exception, but the first lookup may call __autoload (or corresponding SPL
> functions) and it can emit error or throw exception.
> 
> The patch provides an additional boolean argument to __autoload() that say
> if class is really required. In case if it false, user code shouldn't emit
> errors or throw exceptions.

There's two problems here:
1. On each access to internal class, like Exception, SPL classes, 
DateTime, reflection classes, etc. - we'd have call to autoload and 
subsequent disk access, maybe more than one if we have include path. 
Performance of it would be awful.
2. All libraries having autoloaders would have to rewrite them to 
support the new mode.

I would propose different solution. When we have unresolved unqualified 
name, we do the following:
1. Check if we already know such class in namespace at compile-time. If 
so, it's resolved.
2. If not, will be resolved at run-time.
3. At run-time, check if we know such class in namespace now. If yes, 
it's resolved.
4. If not, check if we know internal class with such name. If yes, it's 
resolved to internal class.
5. If not, try to autoload this class. If autoloading fails, it's the 
undefined class error.

This rule is a bit more complex, but allows to resolve common cases 
without extra filesystem accesses and allows to keep autoloader without 
modification.

Comments?
-- 
Stanislav Malyshev, Zend Software Architect
stas@zend.com   http://www.zend.com/
(408)253-8829   MSN: stas@zend.com