Sent from my iPad

On Jun 16, 2016, at 5:20 AM, Brent Royal-Gordon via swift-evolution 
<swift-evolution@swift.org> wrote:

>> 6. With the core team tied up at WWDC, you may want to temporarily forbid 
>> the use of `private` on a type and revisit the matter when people are less 
>> busy; if necessary, we could even ship Swift 3 that way. Or you may want to 
>> consider making a guess as to a good implementation model to apply. Two 
>> suggestions for alternate implementation models:
>> 
>> a. Introduce a `parent` access level, meaning "visible in scopes within this 
>> file where the parent is visible", which is between `fileprivate` and 
>> `private`. Just as `internal` is the maximum inherited access level, 
>> `parent` is the minimum, so the members of a `private` type would inherit 
>> `parent` visibility. `parent` might be an entirely compiler-internal 
>> concept, with no utterable access control keyword.
> 
> Thinking about this more, I notice that `fileprivate` as currently defined 
> doesn't actually make any sense to say inside a `private` type: if your 
> parent type has less-than-file-wide visibility, nothing in the file that's 
> outside its scope can see you anyway. Therefore, we could redefine 
> `fileprivate` thusly:
> 
>    1. A member with `fileprivate` visibility is visible within the scope in 
> which the nearest containing `private` type is visible.
>    2. If there are no containing `private` types, it is visible within the 
> file containing it.
>    3. Just as the members of a `public` type are `internal`, so the members 
> of a `private` type are `fileprivate`.
> 
> This kind of suggests that we ought to rename `fileprivate` to something 
> that, y'know, doesn't say "file" in it. However, I can scarcely imagine the 
> results of a round of bikeshedding without parental supervision from the core 
> team, so I don't dare make any suggestions.

I am not convinced this is necessary.  If there *is* a containing 'private' 
scope you can just leave the member unannotated to get this behavior.  If there 
isn't you can use 'fileprivate' as it is already defined.  Why is that not 
sufficient?

If you really want a second, more nuanced and complex scope-dependent access 
control mechanism I think you'll need to submit a proposal for it.  A simple 
renaming to 'fileprivate' is what has been accepted thus far.  

The main argument for what you suggest is that it would provide a way to ensure 
visibility of the member is*never* more than the file, but is as visible as 
possible within the file, while being less sensitive to changes in visibility 
of surrounding scopes.  IMO we need to get some experience with SE-0025 in real 
code before we know whether this is a problem that needs solving or not.

-Matthew

> 
> -- 
> Brent Royal-Gordon
> Architechies
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution

_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution

Reply via email to