<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="">The clean way would be to make it an enum with var signum that would return -1, 0, 1:<div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">enum</span><span style="font-variant-ligatures: no-common-ligatures" class=""> IntegerSign<NumberType: SignedNumberType> {</span></div><p style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; min-height: 10px;" class=""><br class="webkit-block-placeholder"></p><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> Negative</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> Zero</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> case</span><span style="font-variant-ligatures: no-common-ligatures" class=""> Positive</span></div><p style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; min-height: 10px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><span class="Apple-tab-span" style="white-space:pre"> </span></span><br class="webkit-block-placeholder"></p><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> var</span><span style="font-variant-ligatures: no-common-ligatures" class=""> signum: </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NumberType</span><span style="font-variant-ligatures: no-common-ligatures" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">switch</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">self</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">case</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Negative:</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">return</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> -</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(39, 42, 216);" class="">1</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">as</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(112, 61, 170);" class="">NumberType</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">case</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Zero:</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">return</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(39, 42, 216);" class="">0</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">as</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(112, 61, 170);" class="">NumberType</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">case</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Positive:</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(187, 44, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">return</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(39, 42, 216);" class="">1</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">as</span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(0, 0, 0);" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(112, 61, 170);" class="">NumberType</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> }</div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div><p style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; min-height: 10px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><span class="Apple-tab-span" style="white-space:pre"> </span></span><br class="webkit-block-placeholder"></p><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; min-height: 10px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">extension</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">SignedNumberType</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo; color: rgb(112, 61, 170);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> var</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> sign: </span><span style="font-variant-ligatures: no-common-ligatures" class="">IntegerSign</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""><</span><span style="font-variant-ligatures: no-common-ligatures" class="">Self</span><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">if</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">self</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> == </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(39, 42, 216);" class="">0</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">return</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Zero</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">} </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">else</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">if</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">self</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> > </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(39, 42, 216);" class="">0</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">return</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Positive</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures;" class="">} </span><span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">else</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> {</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: rgb(187, 44, 162);" class="">return</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> .Negative</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> }</div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div><div style="margin: 0px; font-size: 9px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">}</span></div></div><div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div><div class="">Charlie<br class=""><div class=""><div class=""><div class=""><div class=""><div class="">
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<br class=""><div><blockquote type="cite" class=""><div class="">On May 23, 2016, at 9:29 AM, Haravikk 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=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Could you give an example of this method’s usage? Surely your value is either positive, negative or zero already, so this method doesn’t return anything more useful.</div><div class=""><br class=""></div><div class="">In other words, anywhere that I might do this:</div><div class=""><br class=""></div><div class=""><font face="Monaco" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>if myValue.sign > 0 { … }</font></div><div class=""><br class=""></div><div class="">I could just as easily do:</div><div class=""><br class=""></div><div class=""><font face="Monaco" class=""><span class="Apple-tab-span" style="white-space:pre"> </span>if myValue > 0 { … }</font></div><div class=""><br class=""></div><div class="">To the same end result surely? Unless I’m missing something it seems redundant.</div><div class=""><br class=""></div><div class="">If there is a use-case for this, would it make more sense to have the return type as an enum with cases for Positive, Negative and Zero?</div><br class=""><div class=""><blockquote type="cite" class=""><div class="">On 22 May 2016, at 08:07, Adam Nemecek 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 dir="ltr" class=""><div class="">Howdy,</div><div class="">I think that the SignedNumberType should implement a method called sign that will return -1 for negative numbers, 0 for 0 and 1 for positive numbers. This is similar to the signum method in e.g. Java and similarly called methods in other languages.</div><div class=""><br class=""></div><div class="">The implementation is fairly straight forward</div><div class=""><br class=""></div><div class="">extension SignedNumberType {</div><div class=""> var sign: Self {</div><div class=""> if self == 0 {</div><div class=""> return 0</div><div class=""> }</div><div class=""> else if self > 0 {</div><div class=""> return 1</div><div class=""> }</div><div class=""> return -1</div><div class=""> }</div><div class="">} </div><div class=""><br class=""></div><div class="">I was trying to implement is without branching by doing (x > 0) - (x < 0) but I couldn't get the types right so I'm open to suggestions.</div><div class=""><br class=""></div><div class=""><br class=""></div></div>
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