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Date: Mon, 20 Aug 2007 22:57:19 -0700
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Subject: Re: [PHP-DEV] [PATCH] allowing multiple namespaces per file plus
 namespaces with brackets
From: stas@zend.com (Stanislav Malyshev)

> What happens if you mix them?  
> 
> <?php 
> namespace baz;
> 
> namespace foo {
>   class Bar {
>     ...
>   }
> }
> ?>

That's not the fun yet. This is:

<?php
namespace baz;

namespace foo { ...whatever... }

class bar {}

?>

Now, is bar in namespace baz or not? I guess it is, otherwise it stops 
making any sense. So now when you see in the code it says "class bar" 
what do you do to know which namespace it is? Right, you go up to the 
code, counting closing and open brackets and hoping you didn't miss any 
and try to figure out if it's that main namespace or one of the other 
ones. Now next question - how ones in namespace foo are supposed to call 
class bar? They'd have to call it by full name, baz::bar, right? Welcome 
back, long names. But wait, we could use an import, right? So now we'd 
have block-local imports. And we'd have to track them per 
namespace-block. BTW, what about imports in baz - are they active in 
foo? What if baz wants to talk to class in foo - should it import it? 
And BTW - how the patch solves it - I didn't read all of it, but not 
sure it does it correctly.

> Would the compiler have a heart attack if someone did:
> 
> <?php
> namespace foo {
>   namespace baz {
>     class Bar { ... }
>   }
> }
> ?>

This syntax implies that baz has access to names in foo. The separate 
syntax doesn't. But that's only part of the story - remember the 
names/imports story above? Now take that and make it unlimited depth 
stack, since you'd have to track everything on *each* nesting level 
separately. I wouldn't want to open this can of worms. That'd produce 
messy engine and messy code.
-- 
Stanislav Malyshev, Zend Software Architect
stas@zend.com   http://www.zend.com/
(408)253-8829   MSN: stas@zend.com