<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><blockquote type="cite" class="">On Apr 27, 2016, at 9:30 AM, Andrew Bennett via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""></blockquote><div><blockquote type="cite" class=""><br class="Apple-interchange-newline"><div class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class="">Sorry if this has been discussed, but have you considered dropping optional entirely, making it throw, and a default implementation that throws a selector not found exception?</span><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class=""><br class=""></div><div class="">This is approximately what you would expect using it in objc. I don't think it has the complexity discussed in the proposals alternatives for other call site issues.<br class=""><br class="">If it throws you can call with "try?" to get similar functionality in most cases.</div><div class=""><br class=""></div><div class="">This assumes that respondsToSelector doesn't pick up the Swift default implementation.</div></div></div></blockquote></div><br class=""><div class="">Is there any case where you’d actually want to display a runtime error as a result of a delegate not implementing an optional method, though? Even setting aside that the method’s supposed to be optional, leaving out a needed delegate method seems more like a programmer error than a runtime error.</div><div class=""><br class=""></div><div class="">Charles</div><div class=""><br class=""></div></body></html>