<div dir="ltr">Okay, I guess it's fair that (T, T?) and (T?, T) overloads should have to be a separate proposal.<div><br></div><div>My personal motivation is mostly anecdotal; I've found them quite useful, and I wouldn't say they're uncommon. Some use cases off the top of my head:<div>- checking whether a dictionary contains a particular value for a key</div><div>- checking whether an optional ivar (such as "selectedIndex: Int?") contains a particular value ("if tappedIndex == selectedIndex")</div><div><div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div>Jacob<br></div></div></div></div>
<br><div class="gmail_quote">On Tue, Jul 12, 2016 at 12:09 AM, Mark Lacey <span dir="ltr"><<a href="mailto:mark.lacey@apple.com" target="_blank">mark.lacey@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word"><br><div><span class=""><blockquote type="cite"><div>On Jul 11, 2016, at 11:55 PM, Jacob Bandes-Storch <<a href="mailto:jtbandes@gmail.com" target="_blank">jtbandes@gmail.com</a>> wrote:</div><br><div><div dir="ltr">Mark,<div>Thanks for writing this up. Just to clarify, will these still work if your proposal is implemented?</div><div><br></div><div> let x: Int?</div><div> let y: Int</div><div> struct NotEquatable {}<br></div><div> let z: NotEquatable?</div><div><br></div><div> x == y; x != y</div><div> x == nil; x != nil</div><div> z == nil; z != nil</div><div class="gmail_extra"><br></div><div class="gmail_extra">I would hope that these continue to work. If any changes need to be made to ensure that, please make sure they're included in the proposal too.</div></div></div></blockquote><div><br></div></span>The last four would work, but the first two (x == y and x != y) would not because they still involve coercing y to an optional.</div><div><br></div><div>Similarly, === and !== on reference types where one is an optional would require coercing one side, and would not be accepted without an explicit cast using Optional().</div><div><br></div><div>I’m curious what the motivation is for further special casing these operators. They do occur more in practice than <, <=, >, >= (in fact most of the source updates I had to make were due to === and !==, with == and != a close second), but overall these are still quite uncommon from what I’ve seen.</div><div><br></div><div>If you’d like I can certainly update the “alternatives considered” to include the suggestion that we add overloads for (T, T?) and (T?, T) for those four operators.</div><span class=""><font color="#888888"><div><br></div><div>Mark</div></font></span><span class=""><div><br><blockquote type="cite"><div><div dir="ltr"><div class="gmail_extra"><br clear="all"><div><div data-smartmail="gmail_signature"><div dir="ltr"><div>Jacob<br></div></div></div></div>
<br><div class="gmail_quote">On Mon, Jul 11, 2016 at 9:35 PM, Mark Lacey <span dir="ltr"><<a href="mailto:mark.lacey@apple.com" target="_blank">mark.lacey@apple.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="word-wrap:break-word"><br><div><div><div><blockquote type="cite"><div>On Jul 11, 2016, at 9:12 PM, Chris Lattner via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>> wrote:</div><br><div><div style="word-wrap:break-word"><br><div><blockquote type="cite"><div>On Jul 11, 2016, at 8:14 PM, Jacob Bandes-Storch via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>> wrote:</div><br><div><div dir="ltr"><div>You'd have to unwrap it, or use the ??/==/!= operators: <a href="https://gist.github.com/jtbandes/9d88cc83ceceb6c62f38" target="_blank">https://gist.github.com/jtbandes/9d88cc83ceceb6c62f38</a></div><div><br></div><div>I'd be okay with </<=/>/>= returning Bool?, as I suggested in an older email (which somehow didn't make it to gmane's archive, but it's quoted in <a href="http://thread.gmane.org/gmane.comp.lang.swift.evolution/10095" target="_blank">some other messages</a>). I think it would be more convenient in some cases than unwrapping the individual values before comparing them.</div></div></div></blockquote><br></div><div>I’d be strongly opposed to those operator returning “Bool?”. Doing so would prevent conforming to Comparable and would be extremely surprising.</div><div><br></div><div>-Chris</div></div></div></blockquote><div><br></div></div></div>I just pushed the current draft of the proposal: <a href="https://github.com/rudkx/swift-evolution/blob/eliminate-value-to-optional-coercion/proposals/0000-disallow-value-to-optional-coercion-in-operator-arguments.md" target="_blank">https://github.com/rudkx/swift-evolution/blob/eliminate-value-to-optional-coercion/proposals/0000-disallow-value-to-optional-coercion-in-operator-arguments.md</a></div><div><br></div><div>I haven’t addressed removal of the ordered comparison operators. I suspect this should be a separate proposal, but I can roll that into this one if it’s desired.</div><div><br></div><div>I’ll update the proposal as the discussion continues until it’s selected for review.</div><span><font color="#888888"><div><br></div><div>Mark</div></font></span><span><div><br></div><div><blockquote type="cite"><div><div style="word-wrap:break-word"><br></div>_______________________________________________<br>swift-evolution mailing list<br><a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a><br><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br></div></blockquote></div><br></span></div></blockquote></div><br></div></div>
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