<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body><div><div style="font-family: Calibri,sans-serif; font-size: 11pt;">Vanderlei, my point in bringing such topics to this discussion is to make everyone here think if we're trying to really enhance the language within its intended purpose or if we're trying to change the language into something else were familiar with from other languages we work/ed with just because we're used to work like that. I just started thinking about this today and just cannot stop now. No intention to start a war here but I think everyone should ask themselves this for every proposed change to the language.<br><br>About the topic at-hand, we have to remember Swift is bridged to Objective-C, which has no protected (or abstract). How do you propose these protected members be bridged should the proposal pass?<br></div></div><div dir="ltr"><hr><span style="font-family: Calibri,sans-serif; font-size: 11pt; font-weight: bold;">From: </span><span style="font-family: Calibri,sans-serif; font-size: 11pt;"><a href="mailto:swift-evolution@swift.org">Vanderlei Martinelli via swift-evolution</a></span><br><span style="font-family: Calibri,sans-serif; font-size: 11pt; font-weight: bold;">Sent: </span><span style="font-family: Calibri,sans-serif; font-size: 11pt;">29/05/2016 06:56 PM</span><br><span style="font-family: Calibri,sans-serif; font-size: 11pt; font-weight: bold;">To: </span><span style="font-family: Calibri,sans-serif; font-size: 11pt;"><a href="mailto:swift-evolution@swift.org">swift-evolution</a></span><br><span style="font-family: Calibri,sans-serif; font-size: 11pt; font-weight: bold;">Subject: </span><span style="font-family: Calibri,sans-serif; font-size: 11pt;">Re: [swift-evolution] [Proposal] Protected Access Level</span><br><br></div><div dir="ltr"><div>Thank you all for your comments. :-)</div><div><br></div><div>Well... My goal is to keep the thing really simple and do not start a new "OOP x POP" (or "something" x "other thing") war.</div><div><br></div><div>"Protected" access level is not a new concept at all (except for the Swift language), so I did not propose anything preposterous.<br></div><div><br></div><div>Of course in the Swift of my dreams we also have "abstract" access level modifier, "protected" access level, *real* "private" access level and "file" access level modifier (along with many, many other things, of course). But this proposal is not about this. It is only about include the "protected" access level.</div><div><br></div><div>There is, however, something that I need to get off my chest: I really would like to have the freedom to go to the depths with protocols as well with classes. I work in real apps everyday that uses Cocoa frameworks (based on classes) and these apps must be shipped and I like them well written. Maybe am I insane for proposing a better support for classes in Swift? If so, this explains why every time I suggest better support for classes in Swift there is an endless discussion and someone proclaims the death of OOP and is it. OK... Maybe someday we will not have more classes in Swift. Until there: the current language status is the best way to handle OOP in Swift? Or is there a better way? I think there is.</div><div><br></div><div><br></div><div>Regards,</div><div><br></div><div>Vanderlei Martinelli</div><div><br></div><div><br></div><div><br></div><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;"><div dir="ltr"><div><br></div><div><br></div></div>
</blockquote></div><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, May 28, 2016 at 7:52 PM, Vanderlei Martinelli <span dir="ltr"><<a href="mailto:vmartinelli@alecrim.com" target="_blank">vmartinelli@alecrim.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;"><div dir="ltr">Hello.<div><br></div><div><br></div><div>This is the first draft. I'd like to know your opinion about it.</div><div><br></div><div>(I know that this subject could have been discussed before. If so, please indicate me the correct thread to follow and interact.)</div><div><br></div><div><br></div><div>Regards,</div><div><br></div><div>Vanderlei Martinelli</div><div><br></div><div><br></div><div>---</div><div><br></div><div><br></div><div><h2 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 24px; border-bottom-color: rgb(204, 204, 204); border-bottom-width: 1px; border-bottom-style: solid;">Introduction</h2><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Protected access level will enable entities to be used within the container type and by derived types only.</p><h2 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 24px; border-bottom-color: rgb(204, 204, 204); border-bottom-width: 1px; border-bottom-style: solid;">Motivation</h2><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Today Swift has three access levels (<code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">public</code>, <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">internal</code> and <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">private</code>), but lacks a way to describe a member that can be only visible to its type or derived types.</p><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">A common case is the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">UIView</code> from UIKit. Many developers are tempted to make this call:</p><div style="color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;"><pre style='padding: 1em 1em 1em 3.8em; border-radius: 3px; border: 1px solid rgb(204, 204, 204); border-image: none; line-height: 1.5; overflow: auto; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; font-size: 13px; margin-top: 0.5em; margin-bottom: 0.5em; word-spacing: normal; -ms-word-wrap: normal; background-color: rgb(245, 242, 240);'><code style='margin: 0px; padding: 0px; border-radius: 3px; border: currentColor; border-image: none; line-height: 1.5; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; word-spacing: normal; -ms-word-wrap: normal; background-image: none;'>view<span style="color: rgb(153, 153, 153);">.</span><span style="color: rgb(221, 74, 104);">layoutSubviews</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span><span style="width: 3em; letter-spacing: -1px; border-right-color: rgb(153, 153, 153); border-right-width: 1px; border-right-style: solid;"><span style="display: block;"></span></span></code></pre></div><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">The documentation says: "You should not call this method directly. If you want to force a layout update, call the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">setNeedsLayout</code>method instead to do so prior to the next drawing update. If you want to update the layout of your views immediately, call the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">layoutIfNeeded</code> method."</p><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">But yes, you should call this method directly if you are subclassing the view and needs to perform additional layout to its subviews ("subclasses can override this method as needed"):</p><div style="color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;"><pre style='padding: 1em 1em 1em 3.8em; border-radius: 3px; border: 1px solid rgb(204, 204, 204); border-image: none; line-height: 1.5; overflow: auto; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; font-size: 13px; margin-top: 0.5em; margin-bottom: 0.5em; word-spacing: normal; -ms-word-wrap: normal; background-color: rgb(245, 242, 240);'><code style='margin: 0px; padding: 0px; border-radius: 3px; border: currentColor; border-image: none; line-height: 1.5; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; word-spacing: normal; -ms-word-wrap: normal; background-image: none;'><span style="color: rgb(0, 119, 170);">public</span> <span style="color: rgb(0, 119, 170);">override</span> <span style="color: rgb(0, 119, 170);">func</span> <span style="color: rgb(221, 74, 104);">layoutSubviews</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span> <span style="color: rgb(153, 153, 153);">{</span>
<span style="color: rgb(112, 128, 144);">// We are calling the super method directly here.</span>
<span style="color: rgb(0, 119, 170);">super</span><span style="color: rgb(153, 153, 153);">.</span><span style="color: rgb(221, 74, 104);">layoutSubviews</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span>
<span style="color: rgb(112, 128, 144);">// Do more adjustments to this view's subviews...</span>
<span style="color: rgb(153, 153, 153);">}</span><span style="width: 3em; letter-spacing: -1px; border-right-color: rgb(153, 153, 153); border-right-width: 1px; border-right-style: solid;"><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span></span></code></pre></div><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">So, yes, we can call this method directly when subclassing, but the Swift compiler will not prevent you from do this when not subclassing or from any other foreign class. It will not even issue a warning.</p><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">In Objective-C problems like this are usually "solved" my adding a kind of "protected" header (<code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">.h</code>) that is intended to be included only when the developer is subclassing. In Swift we do not have headers, but we have the new access level model. So, if the declaration of this method was...</p><div style="color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;"><pre style='padding: 1em 1em 1em 3.8em; border-radius: 3px; border: 1px solid rgb(204, 204, 204); border-image: none; line-height: 1.5; overflow: auto; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; font-size: 13px; margin-top: 0.5em; margin-bottom: 0.5em; word-spacing: normal; -ms-word-wrap: normal; background-color: rgb(245, 242, 240);'><code style='margin: 0px; padding: 0px; border-radius: 3px; border: currentColor; border-image: none; line-height: 1.5; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; word-spacing: normal; -ms-word-wrap: normal; background-image: none;'>protected <span style="color: rgb(0, 119, 170);">func</span> <span style="color: rgb(221, 74, 104);">layoutSubviews</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span><span style="width: 3em; letter-spacing: -1px; border-right-color: rgb(153, 153, 153); border-right-width: 1px; border-right-style: solid;"><span style="display: block;"></span></span></code></pre></div><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">... no one outside the class or derived classes would be allowed to call this method directly.</p><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Of course, there are other cases in the Cocoa frameworks and there are many other cases when we are developing software in Swift that the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">protected</code> access level would be very usefull.</p><h2 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 24px; border-bottom-color: rgb(204, 204, 204); border-bottom-width: 1px; border-bottom-style: solid;">Proposed solution</h2><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Create the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">protected</code> access level.</p><h2 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 24px; border-bottom-color: rgb(204, 204, 204); border-bottom-width: 1px; border-bottom-style: solid;">Detailed design</h2><h3 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 18px;">Reference Types (classes)</h3><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">When declarated by a <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">class</code> the protected member will be visible to the class itself and all the derived classes.</p><div style="color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;"><pre style='padding: 1em 1em 1em 3.8em; border-radius: 3px; border: 1px solid rgb(204, 204, 204); border-image: none; line-height: 1.5; overflow: auto; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; font-size: 13px; margin-top: 0.5em; margin-bottom: 0.5em; word-spacing: normal; -ms-word-wrap: normal; background-color: rgb(245, 242, 240);'><code style='margin: 0px; padding: 0px; border-radius: 3px; border: currentColor; border-image: none; line-height: 1.5; font-family: Consolas,Monaco,"Andale Mono","Ubuntu Mono",monospace; word-spacing: normal; -ms-word-wrap: normal; background-image: none;'><span style="color: rgb(112, 128, 144);">// BaseClass.swift</span>
<span style="color: rgb(0, 119, 170);">public</span> <span style="color: rgb(0, 119, 170);">class</span> <span>BaseClass</span> <span style="color: rgb(153, 153, 153);">{</span>
<span style="color: rgb(0, 119, 170);">public</span> <span style="color: rgb(221, 74, 104);">protected</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(0, 119, 170);">set</span><span style="color: rgb(153, 153, 153);">)</span> <span style="color: rgb(0, 119, 170);">var</span> x <span style="color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039);">=</span> <span style="color: rgb(153, 0, 85);">20</span>
protected <span style="color: rgb(0, 119, 170);">let</span> y <span style="color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039);">=</span> <span style="color: rgb(153, 0, 85);">10</span>
protected <span style="color: rgb(0, 119, 170);">func</span> <span style="color: rgb(221, 74, 104);">doSomething</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span> <span style="color: rgb(153, 153, 153);">{</span>
<span style="color: rgb(112, 128, 144);">// ...</span>
<span style="color: rgb(153, 153, 153);">}</span>
<span style="color: rgb(153, 153, 153);">}</span>
<span style="color: rgb(112, 128, 144);">// DerivedClass.swift</span>
<span style="color: rgb(0, 119, 170);">public</span> <span style="color: rgb(0, 119, 170);">class</span> <span>DerivedClass</span><span style="color: rgb(153, 153, 153);">:</span> <span style="color: rgb(102, 153, 0);">BaseClass</span> <span style="color: rgb(153, 153, 153);">{</span>
protected <span style="color: rgb(0, 119, 170);">override</span> <span style="color: rgb(221, 74, 104);">doSomething</span><span style="color: rgb(153, 153, 153);">(</span><span style="color: rgb(153, 153, 153);">)</span> <span style="color: rgb(153, 153, 153);">{</span>
<span style="color: rgb(0, 119, 170);">self</span><span style="color: rgb(153, 153, 153);">.</span>x <span style="color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039);">=</span> <span style="color: rgb(153, 0, 85);">10</span> <span style="color: rgb(166, 127, 89); background-color: rgba(255, 255, 255, 0.498039);">*</span> <span style="color: rgb(0, 119, 170);">self</span><span style="color: rgb(153, 153, 153);">.</span>y
<span style="color: rgb(153, 153, 153);">}</span>
<span style="color: rgb(153, 153, 153);">}</span><span style="width: 3em; letter-spacing: -1px; border-right-color: rgb(153, 153, 153); border-right-width: 1px; border-right-style: solid;"><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span><span style="display: block;"></span></span></code></pre></div><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">If the member is declared as <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">final</code> then it will be visible but not can be overrided by the derived classes. Just like it works with other access levels.</p><h3 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 18px;">Value Types (structs, enums, etc.)</h3><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Value types cannot have derived types. In this case the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">protected</code> access level does not make sense and will not be allowed in their members.</p><h3 style="margin: 20px 0px 10px; padding: 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 18px;">Protocols</h3><p style="margin: 15px 0px; color: rgb(0, 0, 0); font-family: Helvetica,arial,sans-serif; font-size: 14px;">Protocols do not declare access level for their members. So the <code style="margin: 0px 2px; padding: 0px 5px; border-radius: 3px; border: 1px solid rgb(234, 234, 234); border-image: none; white-space: nowrap; background-color: rgb(248, 248, 248);">protected</code>�</p></div></div></blockquote></div></div><br><div>[The entire original message is not included.]</div></body></html>