<div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">Hi Nate,</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">It my personal habit to use do-block to compare different Objects with the same name. For example,</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">do</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures"> A {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">// some staff</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">A</span><span style="font-variant-ligatures:no-common-ligatures">()</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">// some other staff</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">do</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures"> A {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> foo() {}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">// some staff</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">A</span><span style="font-variant-ligatures:no-common-ligatures">()</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">// some other staff</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">I don't need to comment/uncomment with do-block when testing my code. </div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">I think for NSObject's `isEqual(_)`, there is a big change and the change is never mentioned in any docs. As far as I know, `==` had never worked with NSObject instances in the past. Because only `isEqual(_)` is used. `==` wouldn't be called at all.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">In today's examples, `==` override the behavior `isEqual(_)`. The change is huge. Because if `==` is never called, someone like me will notice and then change his own code to override `isEqual(_)`. Now `isEqual(_)` is some how abandoned if `==` and `!=` is implemented. That never happens before.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">// prior Swift, NSObject instances</div><div class="gmail_default" style="font-family:georgia,serif">find code `a==b`, call `a.isEqual(b)`</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">// now Swift,</div><div class="gmail_default" style="font-family:georgia,serif">find code `a==b`, call ` if has operator `==``, call `a==b`; else call `a.isEqual(b)`</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Zhaoxin</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Apr 19, 2017 at 11:31 AM, Nate Birkholz <span dir="ltr"><<a href="mailto:nbirkholz@gmail.com" target="_blank">nbirkholz@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">I'm not sure exactly how class declarations interact with the scope of a do{ } statement. I declare a new static function inside your do{ } scope and it works fine, but something about the mapping of `==` and `!=` to `isEqual` in NSObject seems to be confused by the scope of the do{ } block. <div><br></div><div>I'm not sure what the use case is for declaring a class inside a do{ } block, but it seems like a bug with SNObject operator mapping:</div><div><div><br></div><div><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,128,0)"><span style="font-variant-ligatures:no-common-ligatures">//: Playground - noun: a place where people can play</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">import</span><span style="font-variant-ligatures:no-common-ligatures"> UIKit</span></p><span class="">
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(4,51,255)"><span style="font-variant-ligatures:no-common-ligatures">do</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">{</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p></span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> testStatic(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">_</span><span style="font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures">(object.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p><span class=""><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> !=(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> != rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p></span><span class=""><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> isEqual(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">_</span><span style="font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">Any</span><span style="font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p></span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(180,38,26)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures">"in isEqual"</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">)</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> object = object </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">as</span><span style="font-variant-ligatures:no-common-ligatures">? </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">_</span><span style="font-variant-ligatures:no-common-ligatures"> = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">super</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">isEqual</span><span style="font-variant-ligatures:no-common-ligatures">(object)</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">if</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> object.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">true</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(4,51,255)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">return</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">false</span></p><span class=""><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a == b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// true</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a != b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// false</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p></span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">Foo</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">.</span><span style="font-variant-ligatures:no-common-ligatures">testStatic</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(a) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// bar</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span>
</p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">output is: </span></p></div></div><blockquote style="margin:0px 0px 0px 40px;border:none;padding:0px"><div><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-size:11px">in isEqual</span></font></p></div></div><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-size:11px">true</span></font></p></div><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-size:11px">in isEqual</span></font></p></div><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-size:11px">false</span></font></p></div><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-size:11px">bar</span></font></p></div></blockquote><font color="#000000" face="menlo"><span style="font-size:11px"><br></span></font><div><p style="margin:0px;line-height:normal"><font color="#000000" face="menlo"><span style="font-variant-ligatures:no-common-ligatures;font-size:11px"></span></font></p></div><div>For the record, enclosing just the statements *outside* the class declaration in a do{ } block works as expected:</div><div><br></div><div><span class=""><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> !=(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> != rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
</span><span class=""><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> isEqual(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">_</span><span style="font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">Any</span><span style="font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
</span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(180,38,26)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures">"in isEqual"</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> object = object </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">as</span><span style="font-variant-ligatures:no-common-ligatures">? </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">_</span><span style="font-variant-ligatures:no-common-ligatures"> = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">super</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">isEqual</span><span style="font-variant-ligatures:no-common-ligatures">(object)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">if</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> object.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">true</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(4,51,255)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">return</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">false</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(4,51,255)"><span style="font-variant-ligatures:no-common-ligatures">do</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">{</span></p><span class="">
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// true</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">!=</span><span style="font-variant-ligatures:no-common-ligatures"> b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// false</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p></span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">output: </span></p></div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">true</span></p></div></blockquote><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">false</span></p></div></blockquote></div><div class="gmail_extra"><div><div class="h5"><br><div class="gmail_quote">On Tue, Apr 18, 2017 at 8:07 PM, Zhao Xin <span dir="ltr"><<a href="mailto:owenzx@gmail.com" target="_blank">owenzx@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">Just put your code in to a do-block. The result will be opposite.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default"><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">do</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">NSObject</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> !=(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> != rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(a == b) </span><span style="font-variant-ligatures:no-common-ligatures">// true, now false</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(a != b) </span><span style="font-variant-ligatures:no-common-ligatures">// false, now true</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)">
</p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p><p style="font-family:menlo;margin:0px;font-size:11px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><br></span></p><p style="margin:0px;line-height:normal;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"><font face="georgia, serif">Zhaoxin</font></span></p></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Apr 19, 2017 at 11:04 AM, Nate Birkholz <span dir="ltr"><<a href="mailto:nbirkholz@gmail.com" target="_blank">nbirkholz@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Your issue seems to be that you created a custom implementation for the `==` operator but not one for the `!=` operator. If I add a custom implementation for `!=` I get the results you expected. Tthe default implementation of NSObject's `isEqual` is a test for identity, like the `===` in Swift. So when you ask "is `a` NOT the same object in memory as `b`?" the object returns "true" because they are indeed not the same object.<div><br></div><div><span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
</span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">func</span><span style="font-variant-ligatures:no-common-ligatures"> !=(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p><span>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
</span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span><span style="font-variant-ligatures:no-common-ligatures"> != rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">name</span></p><span>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(4,51,255)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(52,149,175)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(180,38,26)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">==</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// true</span></p>
</span><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(52,149,175)"><span style="font-variant-ligatures:no-common-ligatures">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">!=</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,143,0)">// false</span></p></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="m_-5172171428729932995m_-4128906517390797318h5">On Tue, Apr 18, 2017 at 7:33 PM, Zhao Xin via swift-users <span dir="ltr"><<a href="mailto:swift-users@swift.org" target="_blank">swift-users@swift.org</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="m_-5172171428729932995m_-4128906517390797318h5"><div dir="ltr"><div class="gmail_default" style="font-family:georgia,serif">Sample 1: both `==` and `!=` is true.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">import</span><span style="font-variant-ligatures:no-common-ligatures"> Foundation</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">==</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// true</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">a</span><span style="font-variant-ligatures:no-common-ligatures"> != </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">b</span><span style="font-variant-ligatures:no-common-ligatures">) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// true</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Sample 2: Add above code to a do-block, behavior changes to expect</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">do</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">NSObject</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a == b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// false</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(a != b) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,132,0)">// true</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif">Sample 3: A little investigation shows that `==` didn't call NSObject's `<span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="color:rgb(0,0,0);font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures"> isEqual(</span><span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="color:rgb(0,0,0);font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">Any</span><span style="color:rgb(0,0,0);font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool` </span>but `!=` did.</div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(112,61,170)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">class</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> Foo:</span><span style="font-variant-ligatures:no-common-ligatures">NSObject</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">init</span><span style="font-variant-ligatures:no-common-ligatures">(name:</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">String</span><span style="font-variant-ligatures:no-common-ligatures">) {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">self</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> = name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">public</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">static</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> ==(lhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">, rhs: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">guard</span><span style="font-variant-ligatures:no-common-ligatures"> type(of:lhs) == type(of:rhs) </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">else</span><span style="font-variant-ligatures:no-common-ligatures"> { </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">false</span><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> lhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">==</span><span style="font-variant-ligatures:no-common-ligatures"> rhs.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">name</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> isEqual(to object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">Any</span><span style="font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"111"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">super</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">isEqual</span><span style="font-variant-ligatures:no-common-ligatures">(to: object)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"> </span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">override</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">func</span><span style="font-variant-ligatures:no-common-ligatures"> isEqual(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">Any</span><span style="font-variant-ligatures:no-common-ligatures">?) -> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(112,61,170)">Bool</span><span style="font-variant-ligatures:no-common-ligatures"> {</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"2222"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">return</span><span style="font-variant-ligatures:no-common-ligatures"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">super</span><span style="font-variant-ligatures:no-common-ligatures">.</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">isEqual</span><span style="font-variant-ligatures:no-common-ligatures">(object)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures"> }</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">}</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> a = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">let</span><span style="font-variant-ligatures:no-common-ligatures"> b = </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">Foo</span><span style="font-variant-ligatures:no-common-ligatures">(name: </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(209,47,27)">"bar"</span><span style="font-variant-ligatures:no-common-ligatures">)</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,0,0);min-height:13px"><span style="font-variant-ligatures:no-common-ligatures"></span><br></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">==</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// true</span></p>
<p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> != </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">) </span><span style="font-variant-ligatures:no-common-ligatures">// 2222, true</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><p style="margin:0px;font-size:11px;line-height:normal;font-family:menlo;color:rgb(0,132,0)"><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">print</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(62,30,129)">!</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">(</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">a</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(49,89,93)">==</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)"> </span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(79,129,135)">b</span><span style="font-variant-ligatures:no-common-ligatures;color:rgb(0,0,0)">)) </span><span style="font-variant-ligatures:no-common-ligatures">// false</span></p></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default" style="font-family:georgia,serif"><br></div><div class="gmail_default"><font face="georgia, serif">So I am wondering what is the future? Will we keep on using `</font><span style="font-family:menlo;color:rgb(0,0,0);font-size:11px;font-variant-ligatures:no-common-ligatures">isEqual(</span><span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">_</span><span style="font-family:menlo;color:rgb(0,0,0);font-size:11px;font-variant-ligatures:no-common-ligatures"> object: </span><span style="font-family:menlo;font-size:11px;font-variant-ligatures:no-common-ligatures;color:rgb(186,45,162)">Any</span><span style="font-family:menlo;color:rgb(0,0,0);font-size:11px;font-variant-ligatures:no-common-ligatures">?)` </span><span style="color:rgb(0,0,0);font-variant-ligatures:no-common-ligatures"><font face="georgia, serif">with class that inherits `NSObject`, or we are trying to drop it?</font></span></div><div class="gmail_default"><span style="color:rgb(0,0,0);font-variant-ligatures:no-common-ligatures"><font face="georgia, serif"><br></font></span></div><div class="gmail_default"><span style="color:rgb(0,0,0);font-variant-ligatures:no-common-ligatures">Xcode 8.3.1 (8E1000a), <span style="font-family:menlo;font-size:11px">3.1 (swiftlang-802.0.51 clang-802.0.41), macOS </span><span style="color:rgb(34,34,34)">10.12.4 (16E195)</span><font face="georgia, serif"><br></font></span></div><div class="gmail_default"><span style="color:rgb(0,0,0);font-variant-ligatures:no-common-ligatures"><font face="georgia, serif"><br></font></span></div><div class="gmail_default"><span style="color:rgb(0,0,0);font-variant-ligatures:no-common-ligatures"><font face="georgia, serif">Zhaoxin </font></span></div></div>
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<br></span></blockquote></div><span class="m_-5172171428729932995m_-4128906517390797318HOEnZb"><font color="#888888"><br><br clear="all"><span class="m_-5172171428729932995HOEnZb"><font color="#888888"><div><br></div>-- <br><div class="m_-5172171428729932995m_-4128906517390797318m_-5891031103006170397gmail_signature" data-smartmail="gmail_signature">Nate Birkholz</div>
</font></span></font></span></div>
</blockquote></div><br></div>
</blockquote></div><br><br clear="all"><div><br></div></div></div><span class="HOEnZb"><font color="#888888">-- <br><div class="m_-5172171428729932995gmail_signature" data-smartmail="gmail_signature">Nate Birkholz</div>
</font></span></div>
</blockquote></div><br></div>