2016/06/15 11:47、Matthew Johnson <matt...@anandabits.com> のメッセージ:
>
>> On Jun 15, 2016, at 1:37 PM, Robert Widmann <devteam.cod...@gmail.com> wrote:
>>
>> The scope of the *declaration* is not the issue. The scope of its *members*
>> is.
>
> Let’s consider an example:
>
> private struct Foo {
> var bar: Int
> }
>
> // elsewhere in the same file:
> var foo = Foo(bar: 42)
> foo.bar = 44
>
> `Foo` is declared private. Private for this declaration is at the file
> scope. The `bar` member has no access modifier so it has the same visibility
> as the struct itself, which is file scope. This will also be true of the
> implicitly synthesized memberwise initializer.
No, it is also private. It does not inherit its parent scope because,
following the letter of the proposal, that symbol will only be visible within
the current declaration. We cannot arbitrarily break access control rules
because it is convenient in one special case.
>
> This means that it is possible to initialize `foo` with a newly constructed
> instance of `Foo` and to modify the `bar` member anywhere else in the same
> file.
bar is not visible here. If it were you could break access control rules.
>
> If `bar` was also declared `private` this would not be possible as its
> visibility would be restricted to the surrounding scope of the initial
> declaration of `Foo`. This means `Foo` would need to provide an explicit
> initializer or factory method with `fileprivate` visibility in order to be
> usable.
bar is private. Declarations within Foo cannot decide to raise that access
level to make themselves more visible. If this should be the case, the
proposal must be amended as much.
>
> Members with no explicit access modifier should have the same *visibility* as
> their containing type (with a maximum implicit visibility of internal), not
> the same *modifier* as their containing type. The only case where there is a
> distinction is the new `private` visibility. Maybe that is what is causing
> the confusion?
That is not what the proposal says. The proposal says it is invisible outside
the current decl, which is the containing structure here.
>
> Does this help?
>
> -Matthew
>
>>
>> ~Robert Widmann
>>
>> 2016/06/15 11:36、Matthew Johnson <matt...@anandabits.com> のメッセージ:
>>
>>> The scope for a top-level declaration is the file itself. This means that
>>> top-level declarations with `private` and `fileprivate` should have the
>>> same behavior. They should not be uninstantiable or unusable.
>>>
>>> -Matthew
>>>
>>>> On Jun 15, 2016, at 1:31 PM, Robert Widmann via swift-evolution
>>>> <swift-evolution@swift.org> wrote:
>>>>
>>>> While implementing SE-0025 (fileprivate), I noticed an interesting bug in
>>>> the proposal. Under the implementation outlined there, any top-level
>>>> structure, class, or enum declared private cannot possibly be instantiated
>>>> and so cannot be used in any way. Because of this, private top-level
>>>> declarations are more often than not blown away entirely by the compiler
>>>> for being unused. It seems strange to me to allow a key language feature
>>>> to act solely as a hint to the optimizer to reduce the size of your
>>>> binary. Perhaps the restrictions around private needs to be relaxed or
>>>> the line between fileprivate and private needs to be investigated again by
>>>> the community before inclusion in the language.
>>>>
>>>> Thoughts?
>>>>
>>>> ~Robert Widmann
>>>> _______________________________________________
>>>> swift-evolution mailing list
>>>> swift-evolution@swift.org
>>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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