<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div><blockquote type="cite" class=""><div class="">On Apr 3, 2017, at 5:32 PM, Daniel Duan <<a href="mailto:daniel@duan.org" class="">daniel@duan.org</a>> wrote:</div><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><blockquote type="cite" class=""><div class="">On Apr 3, 2017, at 2:22 PM, John McCall via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Apr 3, 2017, at 5:21 PM, David Hart <<a href="mailto:david@hartbit.com" class="">david@hartbit.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 3 Apr 2017, at 23:19, John McCall <<a href="mailto:rjmccall@apple.com" class="">rjmccall@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Apr 3, 2017, at 5:11 PM, David Hart via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On 3 Apr 2017, at 22:54, Douglas Gregor via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Apr 3, 2017, at 1:13 PM, Matthew Johnson <<a href="mailto:matthew@anandabits.com" class="">matthew@anandabits.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class=""><br class="Apple-interchange-newline">On Apr 3, 2017, at 2:55 PM, Daniel Duan via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">I’m concerned that we will have access control changes in a future version yet again, when light-weight modules, or other type of enforced namespace is introduced. Does the core team have any foresight on how this change would interact with such things? I had the same concern for SE-0159 as well. <div class=""><br class=""></div><div class="">There’s a implicit drawback to all access control changes that migrator/fix-its cannot fix: we organize our code with tools in the language. Some colleague of mine had came up with schemes that combines file scope and Swift 3 `private` to hide details among separate protocol extensions, for example. Code ends up in certain places for a reason and updating access control invalidate those reasons.</div><div class=""><br class=""></div><div class="">I hesitate to support any changes until we have some ideas for what “ultimate glory” looks like.<br class=""></div></div></div></blockquote><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">+1. </div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""></div><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">If we must make a change in Swift 4, the only change I can support for Swift 4 is renaming the existing access levels. </div></div></blockquote><div class=""><br class=""></div><div class="">We don’t have to make a change in Swift 4. If there’s a change that can resolve this issue, great…</div></div></div></div></blockquote><div class=""><br class=""></div><div class="">I still think this is a worthwhile goals.</div><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><blockquote type="cite" class=""><div class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">That would cause some churn but can be automated and has no semantic impact. I feel strongly that the semantics of access control should remain the same until submodules and access control can be considered together as part of the theme of a larger Swift release. I believe the churn caused by continuing to poke at the semantics of access control without addressing the broader issues would be a mistake that would cause further frustration in the community. </div></div></blockquote><div class=""><br class=""></div>… but if not, then let’s shelve access control changes until some time when we can considered it holistically with something like submodules, as you note above.</div></div></div></blockquote><div class=""><br class=""></div><div class="">Won’t making big modifications later be even more problematic than now, in the name of source stability?</div></div></div></blockquote><div class=""><br class=""></div>Yes. Big changes along these lines will not be considered later. At best, it would be possible to "re-cast" existing behaviors in light of new features — that is, significantly changing *how we talk about those behaviors*, and changing how we understand them in the broader language, but not actually changing the behaviors themselves.</div></div></div></blockquote><div class=""><br class=""></div><div class="">That’s why I don’t buy the “lets postpone this discussion to a future submodule design” argument. Let’s get this in a reasonable state now :)</div></div></div></div></blockquote><div class=""><br class=""></div>I agree. This is why we asked swift-evolution to consider this last tweak: it is realistically the last opportunity to do it.</div></div></blockquote><div class=""><br class=""></div><div class="">Questions:</div><div class=""><br class=""></div><div class="">1. does this mean no changes like this will happen to Swift 5?</div></div></div></div></blockquote><div><br class=""></div>I think it is likely that we will not accept any proposals that change the basic rules of existing language features, no, unless it's a very serious problem or a very minor change.</div><div><br class=""></div><div><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class="">2. can core team provide any discussions/thoughts that they had about submodules, for a “future consideration” section in this proposal?</div></div></div></div></blockquote><div><br class=""></div>We have not had any serious conversations about submodules.</div><div><br class=""></div><div>John.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class=""><div class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">John.</div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="">John.</div><div class=""><br class=""></div><div class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><br class=""><blockquote type="cite" class=""><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><blockquote type="cite" class=""><div class=""><div class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">As others have already pointed out, code has been developed and organized with the new scoped access model in mind. I think the frustration over a semantically neutral, fully automated migration to new names would be pretty minimal </div></div></blockquote><div class=""><br class=""></div><div class="">The core team felt strongly that we couldn’t change these keywords. Source stability is important to Swift 4, and “don’t break source compatibility so much” is one of the top requests we hear from Swift developers, much more so than requests for specific new language features.</div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div class="">and certainly much less than the frustration over the suggested semantic change. </div></blockquote><br class=""></div><div class="">This isn’t clear to me. There could certainly be frustration over the suggested semantic change, for a number of reasons:</div><div class=""><br class=""></div><div class="">* It’s not as “tight” a meaning of private as the current scope-based private.</div><div class="">* It means we have a hybrid type-based/scope-based model.</div><div class="">* It’s the third meaning of ‘private’ in three years.</div><div class=""><br class=""></div><div class="">However, it is unlikely to break code (one would need to construct an ambiguity between two private declarations in different extensions of the same type in the same file), and causes zero code churn, because it’s widening the meaning of “private”, not changing it.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>- Doug</div></div><div class=""><br class=""><blockquote type="cite" class=""><div class=""><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><blockquote type="cite" class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><div class=""><div class=""><br class=""></div><div class=""><div class=""><div class=""><blockquote type="cite" class=""><div class="">On Apr 3, 2017, at 11:34 AM, Douglas Gregor via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hello Swift Community,<div class=""><br class=""></div><div class="">In rejecting <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0159-fix-private-access-levels.md" class="">SE-0159</a>, the core team described a potential direction we would like to investigate for “private” access control that admits a limited form of type-based access control within files. The core team is seeking some discussion here and a motivated volunteer to put together a proposal along these lines for review in the Swift 4 time-frame (i.e., very soon). To be clear, the core team it’s sure this is the right direction to go… but it appears promising and we would *love* to be able to settle the access-control issue.</div><div class=""><br class=""></div><div class="">The design, specifically, is that a “private” member declared within a type “X” or an extension thereof would be accessible from:</div><div class=""><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>* An extension of “X” in the same file</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>* The definition of “X”, if it occurs in the same file</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>* A nested type (or extension thereof) of one of the above that occurs in the same file</div><div class=""><br class=""></div><div class="">This design has a number of apparent benefits:</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ “private” becomes the right default for “less than whole module” visibility, and aligns well with Swift coding style that divides a type’s definition into a number of extensions.</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ “fileprivate” remains for existing use cases, but now it’s use it more rare, which has several advantages:</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ It fits well with the "progressive disclosure” philosophy behind Swift: you can use public/internal/private for a while before encountering and having to learn about “fileprivate” (note: we thought this was going to be true of <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0025-scoped-access-level.md" class="">SE-0025</a>, but we were clearly wrong)</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ When “fileprivate” occurs, it means there’s some interesting coupling between different types in the same file. That makes fileprivate a useful alert to the reader rather than, potentially, something that we routinely use and overlook so that we can separate implementations into extensions.</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ “private” is more closely aligned with other programming languages that use type-based access control, which can help programmers just coming to Swift. When they reach for “private”, they’re likely to get something similar to what they expect—with a little Swift twist due to Swift’s heavy use of extensions.</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>+ Loosening the access restrictions on “private” is unlikely to break existing code.</div><div class=""><br class=""></div><div class="">There are likely some drawbacks:</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>- Developers using patterns that depend on the existing lexically-scoped access control of “private” may find this new interpretation of “private” to be insufficiently strict</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>- Swift’s access control would go from “entirely lexical” to “partly lexical and partly type-based”, which can be viewed as being more complicated</div><div class=""><br class=""></div></div><div class="">Thoughts? Volunteer?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>- Doug</div></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></blockquote></div><br class=""></div></div></div></div></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div></blockquote></div><br class=""></div>_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""></div></blockquote></div><br class="" style="font-family: Helvetica; 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