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.send { color:#77bb77; }
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.error { color:#AA0000; }</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="bloop_markdown"><p>Ugh, this is a bad one, nice catch. I personally never bumped into that, but I’ll be careful from now on that one. Thanks for sharing it.</p>
<p>I’m interested to see the outcome of this pitch. :)</p>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <br> <div id="bloop_sign_1486757241588489984" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 10. Februar 2017 um 20:41:57, Robert Ryan via swift-evolution (<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div></div><div>
<title></title>
As we all know, if you override the default implementation of a
protocol, if you call the method from the protocol reference, the
protocol’s default implementation will be called, not the override
of that method. For example:
<div class=""><br class=""></div>
<div class="">
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">protocol</span> <span style="font-variant-ligatures: no-common-ligatures" class="">Fooable
{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> // this is intentionally
blank</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(186, 45, 162);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures" class="">extension</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Fooable</span> <span style="font-variant-ligatures: no-common-ligatures; color: #000000" class="">{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span> <span style="font-variant-ligatures: no-common-ligatures" class="">foo()
{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span>
<span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"foo"</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">class</span> <span style="font-variant-ligatures: no-common-ligatures" class="">FooBar:</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Fooable</span> <span style="font-variant-ligatures: no-common-ligatures" class="">{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span> <span style="font-variant-ligatures: no-common-ligatures" class="">foo()
{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span>
<span style="font-variant-ligatures: no-common-ligatures; color: #3e1e81" class="">print</span><span style="font-variant-ligatures: no-common-ligatures" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"foobar"</span><span style="font-variant-ligatures: no-common-ligatures" class="">)</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span> <span style="font-variant-ligatures: no-common-ligatures" class="">performFoo(object:</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Fooable</span><span style="font-variant-ligatures: no-common-ligatures" class="">)
{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> object.</span><span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">foo</span><span style="font-variant-ligatures: no-common-ligatures" class="">()</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""><br class=""></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span> <span style="font-variant-ligatures: no-common-ligatures" class="">foobar
=</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">FooBar</span><span style="font-variant-ligatures: no-common-ligatures" class="">()</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">performFoo</span><span style="font-variant-ligatures: no-common-ligatures" class="">(object:</span> <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foobar</span><span style="font-variant-ligatures: no-common-ligatures" class="">)
// prints “foo”, not “foobar"</span></div>
</div>
<div class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div>
<div class="">But, the behavior changes you change the default
method to be part of the protocol, itself:</div>
<div class=""><br class=""></div>
<div class="">
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">protocol</span> <span style="font-variant-ligatures: no-common-ligatures" class="">Fooable
{</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> </span> <span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">func</span> <span style="font-variant-ligatures: no-common-ligatures" class="">foo()</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> }</span></div>
</div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> // the rest as above</span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><br class=""></span></div>
<div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> <span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">performFoo</span>(object: <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">foobar</span>) // prints
“foobar”</span></div>
<div class=""><br class=""></div>
<div class="">I would like to propose that any class that overrides
a protocol’s default implementation where the method is not part of
the protocol, itself, results in a warning. I’m hard pressed to
think of a situation where you’d want the current Swift 3 behavior
of the first example (where you can override a protocol default
implementation but you only want that override used when you
reference the class itself, but not when you reference the protocol
as a type). If there are such examples, then add a “build setting”
to allow you to turn off this warning, or add some keyword to the
declaration of the default implementation that indicates that
you’re allowing it to be overridden, but protocol types won’t use
it (e.g. <span style="color: rgb(186, 45, 162); font-family: Menlo; font-size: 11px;" class="">nondynamic</span>). Personally, I’d just add the warning
and call it a day (because I don’t know why you’d ever want the
current Swift 3 behavior).</div>
<div class=""><br class=""></div>
_______________________________________________<br>swift-evolution mailing list<br>swift-evolution@swift.org<br>https://lists.swift.org/mailman/listinfo/swift-evolution<br></div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>