<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div><br></div><div><br>On 11 Apr 2017, at 09:40, John McCall <<a href="mailto:rjmccall@apple.com">rjmccall@apple.com</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=utf-8"><div><blockquote type="cite" class=""><div class="">On Apr 11, 2017, at 1:34 AM, David Hart via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><div class=""><div dir="auto" class=""><div class=""><div class=""><br class="">Sent from my iPhone</div>On 11 Apr 2017, at 01:37, Ricardo Parada via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><meta http-equiv="content-type" content="text/html; charset=utf-8" class=""><div class="">I have not voted in favor or against the proposal. I have been reading a lot of responses but I agree with Tony. </div><div class=""><br class=""></div><div class="">When I started reading the proposal everything was more or less fine half way through the proposal because it was reverting private to fileprivate between the type and its extensions within the same file. I said, if you think of the type and its extensions as a unit then it makes sense. I can explain that. </div><div class=""><br class=""></div><div class="">Then it started describing a different behavior among the extensions located in a file separate from the file containing the definition of the type. That just started a whole debate inside my head and I understand the passionate responses on both sides. </div><div class=""><br class="">But then I imagined myself explaining this to someone new to Swift and it just doesn't seem right. If it becomes convoluted then that's a red flag that it does not belong in Swift. </div></div></blockquote><div class=""><br class=""></div><div class="">I understand what you are saying and I wouldn't be against relaxing that requirement (not talking for Chris here).</div><div class=""><br class=""></div><div class="">The model would change from "Types share scopes with their extensions in the same file the type was defined" to "Types and their extensions share the same scope in each file".</div></div></div></blockquote><div><br class=""></div>Oh, I had missed that somehow. I agree that that is a very strange rule. Do you know why it was proposed that way?</div></div></blockquote><div><br></div><div>We had to take a stance and Chris seemed to prefer the rule that was proposed. I didn't press because I'm sure he has reasons for preferring it that way. But I have a preference for generalizing visibility to all extensions, even to those in a different file than the type.</div><br><blockquote type="cite"><div><div>John.</div><div><br class=""><blockquote type="cite" class=""><div class=""><div dir="auto" class=""><br class=""><blockquote type="cite" class=""><div class=""><div class="">I agree fileprivate may be ugly to some and it may be more popular than private. But I think fileprivate is very clear. I know what it does from its name without having to ask. And private behaves the way private works in other languages. </div><div class=""><br class=""></div><div class="">Regards</div><div class=""><br class=""></div><div class=""><br class="">On Apr 10, 2017, at 1:35 PM, Tony Allevato via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></div><blockquote type="cite" class=""><div class=""><div dir="ltr" class=""><br class=""><br class=""><div class="gmail_quote"><div dir="ltr" class="">On Mon, Apr 10, 2017 at 9:49 AM Tino Heth <<a href="mailto:2th@gmx.de" class="">2th@gmx.de</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><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" class="gmail_msg">But even outside the generated code use cases, it's nice to just be able to implement helpers or additional "convenience" conformances in separate files named appropriately (like "Type+Protocol.swift" or "Type+Helpers.swift"). I find it makes my codebase easier to navigate.</div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg">No doubt about the usefulness of having separate files with extensions here</div></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><blockquote type="cite" class="gmail_msg"><blockquote class="gmail_quote gmail_msg" 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;margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div class="gmail_msg" style="word-wrap:break-word"><div class="gmail_msg">If nothing else, nested extensions could save those who actually don't care much about such issues from another breaking change in Swift — and imho it adds consistency:</div><div class="gmail_msg">We can nest types, so why can't we nest extensions?</div></div></blockquote><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" class="gmail_msg"><br class="gmail_msg"></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" class="gmail_msg">Because types and extensions are quite different beasts, so something that applies to one doesn't necessarily apply to the other. </div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg">I don't buy this argument at all without an objective explanation why the curly braces of extensions should be treated different than the curly braces of types...</div></div></div></blockquote><div class=""><br class=""></div><div class="">They shouldn't be. That's why I don't support SE-0169 either, because it would allow extensions to extend the *scope* rather than the *type*, but only within the same file. I think that's fundamentally broken.</div><div class=""><br class=""></div><div class="">But my comment wasn't about curly braces—it was about types vs. extensions. For example, you can declare local types within a function, but you can't extend a type within a function (nor do I think it would be a good idea).</div><div class=""><br class=""></div><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"></div><blockquote type="cite" class="gmail_msg"><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" class="gmail_msg">I don't think that holds its weight. This feels like another case of "let's try to satisfy everyone who's unhappy with some part of Swift visibility by changing a completely different feature to make things fall into place", which I don't think is a sound motivation or design principle. The example you posted in your initial message weaves multiple types/nesting levels together in a way that looks *incredibly* difficult to follow/parse to even an experienced user of the language.</div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg">Did you noticed that I started this example as mockery? In real life, I would hopefully never nest more than once… and do you think sprinkling parts of class over the project is easier to follow?</div></div></div></blockquote><div class=""><br class=""></div><div class="">Depending on the type, yes. I wouldn't sprinkle the *fundamental/core* parts of a type across the project, but if there's some kind of "aside" functionality that doesn't depend on private knowledge of the type, then I find it to be a nice feature to have. It requires me to have reasonable names to my source files, but that's not a significant burden.</div><div class=""><br class=""></div><div class=""> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><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" class="gmail_msg">Everyone seems to be striving for a "perfect" level of access control that lets individual types/members dictate precisely what other types/members can access them. I'm not sure if that perfection is attainable or not, but even if it is, I don't think it's something we should strive for. I'd rather have a simple visibility model that leaks a little than an air-tight model that allows people to write overly complicated code for the sake of fine-tuning access.</div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><div class="gmail_msg">I had no desire to change the model of Swift 2 — but apparently, others thought it wasn't sufficient, and I'd rather prefer a conceptually simple model like nesting over a complicated one with less power.</div></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"><br class="gmail_msg"><blockquote type="cite" class="gmail_msg"><div class="gmail_msg"><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" class="gmail_msg">Let's remember that the core team has limited resources to implement the things we propose, and if I have to choose between, say, serialization, reflection, asynchronous constructs, and rehashing visibility levels yet again, it's clear to me which one I would want dropped on the floor. I don't want perfect to be the enemy of good.</div></div></blockquote></div></div><div style="word-wrap:break-word" class="gmail_msg"><div class="gmail_msg"></div>Well, right now, there are several (at least one ;-) proposals that aim for a breaking change of the whole model… nested extensions break nothing, so it can be delayed for as long as the core team likes, without causing any trouble.</div></blockquote><div class=""> <br class=""></div></div></div>
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