<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=""><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 3, 2017, at 10:54 AM, Thorsten Seitz <<a href="mailto:tseitz42@icloud.com" class="">tseitz42@icloud.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div class="Singleton" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""><blockquote type="cite" class="" 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-size-adjust: auto; -webkit-text-stroke-width: 0px;"><div class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space;"><div class=""><div class=""><br class="Apple-interchange-newline">At that point, there would be a general uproar because IUOs have high potential for abuse: Swift is “all about” strong types and safety, which IUOs undermine. Strong optionals are considered a pain to use by some people and widely misunderstood (I think they are the biggest challenge in learning Swift in practice), and so it is a reasonable feature that people could pervasively adopt IUOs, leading to a much worse world all around.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">This made up parallel universe is exactly analogous to what is happening now. DynamicMemberLookup is no more dangerous and harmful than IUOs are. </div></div></div></div></blockquote><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">The difference is that IUOs are marked by a "!“ whereas dynamic member lookups look just like normal member lookups but unlike them can fail.</div></div></div></div></blockquote><br class=""></div><div>Matthew was primarily concerned about point of use, in which IUO dereferencing is completely implicit and invisible.</div><div><br class=""></div><div>-Chris</div><div><br class=""></div></body></html>