> On Apr 22, 2017, at 12:30 PM, Xiaodi Wu <[email protected]> wrote:
> 
>> On Sat, Apr 22, 2017 at 11:51 AM, Jose Cheyo Jimenez via swift-evolution 
>> <[email protected]> wrote:
>> 
>> 
>>> On Apr 21, 2017, at 8:41 PM, BJ Homer via swift-evolution 
>>> <[email protected]> wrote:
>>> 
>>> The "Access Control" section of the Swift 3 book says the following:
>>>> You can mark an extension with an explicit access-level modifier (for 
>>>> example, private extension) to set a new default access level for all 
>>>> members defined within the extension.
>>> The behavior of "private extension" in Swift 3 was a deviation from that 
>>> model, justified because "private" as a default would have meant that 
>>> nothing in the extension could ever be called. But it was still contrary to 
>>> the model suggested by the Swift documentation. 
>>> 
>>> Given the highly restrictive behavior of "private" in Swift 3 and the 
>>> documentation quoted above, it seems unlikely that a developer would 
>>> intentionally use "private extension" to mean "please make all this stuff 
>>> visible to the entire file"—it would have worked, but it seems an odd way 
>>> to write it. If that were the intention, I think "fileprivate extension" 
>>> would have been more likely.
>>> 
>>> I think the change to the behavior of "private extension" is in line with 
>>> the model proposed by SE-0169, in line with the documented behavior of 
>>> access control on extensions, and in line with user expectations.
>>> 
>>> -BJ
>> 
>> I understand your point. Another aspect of SE-0169 is that fileprivate 
>> should be more rare and thus meaningful when used. The current behavior 
>> stays true to the goal of making fileprivate rare. 
>> 
>> A top level private scope is effectively fileprivate so it is not totally 
>> weird for the extension members to inherit the top level private scope. 
>> 
>> When extensions gain the ability to contain properties, we should not allow 
>> the access level modifiers to the extensions in the same way protocol 
>> extensions prohibit its use. 
> 
> That idea would be my preference too, but it has been already written up as a 
> proposal, considered, and rejected.

Properties in extensions? AKA partials ? I was thinking disallow only when 
properties are introduced in the extension not in general. 
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