<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><br><div id="AppleMailSignature">Sent from my iPhone</div><div><br>On 3 Aug 2017, at 01:09, Jordan Rose via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div class=""><b class=""><br class=""></b></div><div class="">'required' initializers are like methods: they may require dynamic dispatch. That means that they get an entry in the class's dynamic dispatch table, commonly known as its <i class="">vtable</i>. Unlike Objective-C method tables, vtables aren't set up to have entries arbitrarily added at run time.</div><div class=""><br class=""></div><div class="">(Aside: This is one of the reasons why non-@objc methods in Swift extensions can't be overridden; if we ever lift that restriction, it'll be by using a separate table and a form of dispatch similar to objc_msgSend. I sent a proposal to swift-evolution about this last year but there wasn't much interest.)</div></div></blockquote><br><div>If I missed replying to that originally I also missed the chance to say that it would be a lovely idea and dynamic dispatch in some cases is just what the doctor ordered (runtime editable method tables).</div><div>This is especially <b>especially important with extensions for classes and default methods (and the current rules for overriding methods in the implementing class)</b>, please resubmit the proposal :).</div></body></html>