> On Aug 28, 2021, at 5:12 PM, Olle Härstedt <olleharst...@gmail.com> wrote: > > 2021-08-27 23:07 GMT+02:00, Rowan Tommins <rowan.coll...@gmail.com > <mailto:rowan.coll...@gmail.com>>: >> On 27/08/2021 20:47, Olle Härstedt 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 higher level than actually how to implement: https://github.com/nikic/php-rfcs/blob/language-evolution/rfcs/0000-language-evolution.md <https://github.com/nikic/php-rfcs/blob/language-evolution/rfcs/0000-language-evolution.md> https://phpinternals.news/45 <https://phpinternals.news/45> -Mike
