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Date: Sun, 29 Aug 2021 10:33:49 +0200
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To: Mike Schinkel <mike@newclarity.net>
Cc: Rowan Tommins <rowan.collins@gmail.com>, internals@lists.php.net
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Subject: Re: [PHP-DEV] Make namespace part of runtime
From: olleharstedt@gmail.com (=?UTF-8?Q?Olle_H=C3=A4rstedt?=)

2021-08-29 5:12 GMT+02:00, Mike Schinkel <mike@newclarity.net>:
>
>
>> On Aug 28, 2021, at 5:12 PM, Olle H=C3=A4rstedt <olleharstedt@gmail.com>
>> wrote:
>>
>> 2021-08-27 23:07 GMT+02:00, Rowan Tommins <rowan.collins@gmail.com
>> <mailto:rowan.collins@gmail.com>>:
>>> On 27/08/2021 20:47, Olle H=C3=A4rstedt wrote:
>>>> As a followup for my previous post, I think this could be a good place
>>>> to start to enable attribute writers to create encapsulation mechanics
>>>> for composition, like namespace visibility, "internal" access or
>>>> friend classes.
>>>
>>>
>>> In my experience PHP projects tend to use namespace hierarchies which
>>> are deep rather than broad, and I'm not sure how easily those
>>> hierarchies could be re-purposed as scopes.
>>>
>>> Clicking through the Symfony source at random for an example, I found
>>> "namespace
>>> Symfony\Component\Messenger\Transport\Serialization\Normalizer", which
>>> contains only one class.
>>>
>>> A trivial implementation of namespace visibility which just matched the
>>> exact namespace string would be completely useless for that class (it
>>> would be the same as "private"). A slightly less trivial
>>> implementationmight allow access from "child namespaces", but that
>>> wouldn't help in this case.
>>>
>>> However, it might be really useful to restrict usage of that class, or
>>> some of its members, to classes in the "Symfony\Component\Messenger"
>>> namespace; or maybe to those in the
>>> "Symfony\Component\Messenger\Transport\Serialization" namespace.
>>>
>>> I can see two ways of enabling that:
>>>
>>> - Allowing visibility modifiers to specify exactly what level of prefix
>>> they refer to. This is apparently how Scala approaches things, allowing
>>> you to write the equivalent of "private[Symfony\Component\Messenger]
>>> $foo; protected[Symfony\Component\Messenger\Transport\Serialization]
>>> $bar;"
>>
>> Yes, I assume this is why Psalm introduced a new annotation
>> @psalm-internal <namespace>, which does take such a parameter. A PHP
>> attribute can do this, _if_ it has access to runtime namespace.
>>
>>> - Introducing a separate concept of "package", either orthogonal to
>>> namespaces or overlapping with them, e.g. "package
>>> Symfony\Component\Messenger; namespace
>>> Transport\Serialization\Normalizer;" would still give a class name
>>> beginning
>>> "Symfony\Component\Messenger\Transport\Serialization\Normalizer", but
>>> would define "internal" to mean accessible within the
>>> "Symfony\Component\Messenger" package.
>>
>> What's the estimated effort for adding package support to PHP? Did
>> anyone outline a possible implementation?
>
> In case you have not seen these, which discuss possibilities but at a hig=
her
> level than actually how to implement:
>
> https://github.com/nikic/php-rfcs/blob/language-evolution/rfcs/0000-langu=
age-evolution.md
> <https://github.com/nikic/php-rfcs/blob/language-evolution/rfcs/0000-lang=
uage-evolution.md>
> https://phpinternals.news/45 <https://phpinternals.news/45>
>
> -Mike

Oh cool, thanks! So there's more support in internals for doing
package-visibility instead of namespace-visibility in the end? Or
maybe the topic is not so hot?

Olle