<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=""><span class="Apple-tab-span" style="white-space:pre"> </span>I can’t answer for Per, but, at least in my iOS and OS X programming, I often find myself creating IUOs in view controller to represent properties that I’m guaranteed to have set before viewDidLoad, but don’t want a custom initializer, due to the pain of multiple required init methods. So while my IUO usage is perfectly safe, they’re rather awkward to use.<div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>That said, I’d have to see a specific proposal to tell if it’s any better for my usage than IUOs.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Jon Shier</div><div class=""><br class=""></div><div class=""><div><blockquote type="cite" class=""><div class="">On Dec 4, 2015, at 7:04 PM, Chris Lattner <<a href="mailto:clattner@apple.com" class="">clattner@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><blockquote type="cite" class=""><div class=""><br class="Apple-interchange-newline">On Dec 4, 2015, at 1:18 PM, Per Melin <<a href="mailto:p@greendale.se" class="">p@greendale.se</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" class=""><div class="">On Fri, Dec 4, 2015 at 1:03 AM, Amir Michail<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:a.michail@me.com" target="_blank" class="">a.michail@me.com</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""></div><div class="gmail_extra"><div class="gmail_quote"><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-color: rgb(204, 204, 204); border-left-style: solid; padding-left: 1ex;"><span class=""><br class=""></span>I really don’t like having to put the ! suffix in boolean contexts:<br class=""></blockquote><div class=""><br class=""></div><div class=""><div class="">To be explicit:</div><div class=""><br class=""></div><div class=""> let a: Bool! = false</div><div class=""><br class=""></div><div class=""> if a == false { } // Works as expected<br class=""></div><div class=""><br class=""></div><div class=""> if !a { } // Works as expected</div><div class=""><br class=""></div><div class=""> if a { } // "error: optional type 'Bool!' cannot be used as a boolean; test for '!= nil' instead"</div></div><div class=""><br class=""></div><div class="">Xcode "fixes" the last line like this:</div><div class=""><br class=""></div><div class=""> if (a != nil) { }<br class=""></div></div></div></div></div></blockquote><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">Huh ok. Out of curiosity, why are you using IUOs for this? I’m interested in (continuing to ) dramatically reduce the prevalence of IOUs in code (eliminating the need to use them), and reduce their power in various ways. IUOs are one of the biggest sources of surprising behavior in Swift, and while they were a necessary feature to start with, their importance is going down over time.</div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><br class=""></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">-Chris</div><br class="" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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;"><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=Ro-2BBk80NUrPWFtcFY6sgkxchOdXD71JI2cxZNLYx0O-2FbZrkZNXu0MeiF8iWQvxN6rv9MieVXwqhh4lh34zCmW1eis3fjomc0cV2dxLA2DjKVEKCaOrcrsKLxj4eB7Etbrd7eHbEXtvvvNx4THlXBPNbrosbu4TsMrgODug2GHa8PvgDfbuO5ZXVzTqfvQwMLpBGvXf2mAiY0WVvOW1qa0g-3D-3D" alt="" width="1" height="1" border="0" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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; height: 1px !important; width: 1px !important; border-width: 0px !important; margin: 0px !important; padding: 0px !important;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><span class="Apple-converted-space"> </span></span><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">_______________________________________________</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">swift-evolution mailing list</span><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><a href="mailto:swift-evolution@swift.org" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">swift-evolution@swift.org</a><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: 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="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div><br class=""></div></body></html>