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Date: Wed, 14 Aug 2019 09:36:26 +0100
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Subject: Re: [PHP-DEV] [RFC] Namespace-scoped declares, again
From: rowan.collins@gmail.com (Rowan Collins)

On 13/08/2019 23:28, Mark Randall wrote:
> On 13/08/2019 21:26, Rowan Collins wrote:
>> Ah, that makes sense. Does that necessarily mean we need a dummy 
>> class, though? The autoloading logic in the engine knows that it 
>> called the autoload callback expecting a package definition, so can 
>> count as success that the package is now defined.
>>
>> In other words, the file the autoloader included would look like this 
>> (again, sticking to the notion that "package" is separate from 
>> "namespace"):
>
> Personally with file-level opt ins I'm not 100% sold on the benefits 
> of packages over namespace level information. I guess I'm not certain 
> on what problem they're trying to solve that's different from just 
> another object at namespace level.


The problem they're trying to solve is that at the moment, there is no 
namespace-level information. Namespaces form an arbitrarily deep 
hierarchy, and don't need to be declared before they're used; it's hard 
to retrofit configuration into that. In my mind a package would be very 
similar to a namespace, but would have a mandatory declaration 
somewhere, giving a place to define its settings and properties; and 
there would be no "sub-packages", so no need to define inheritance and 
over-rides.


> As for the dummy class, the only real benefit is that existing 
> autoloading procedures can be used to locate it and be included with 
> minimal overhead.
>
> PHP can call the autoloader internally but it would require userland 
> loaders to be upgraded with it, not exactly a huge stretch, especially 
> with most things being composer-based, but a dummy class would make it 
> work out the box, including optimization steps like dumping the class 
> list.


I see what you mean; but the change needed to autoloaders would be 
pretty minimal: if they just turn the name into a file path and run 
file_exists(), no change at all; if they tokenize files in advance to 
build a class map, they would need to add "packagedef" to the list of 
tokens to search for, alongside "class", "interface", and "trait". The 
same change would be needed if we introduced a "struct" or "enum" 
keyword, and I don't think anyone would expect to write dummy classes 
alongside those.


Regards,

-- 
Rowan Collins
[IMSoP]