<html><head><meta http-equiv="Content-Type" content="text/html charset=us-ascii"></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 17, 2015, at 4:36 PM, Joe Groff via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div 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="">There are several advantages over IUO that I see. The behavior can ensure that a mutable delayed var never gets reset to nil, and can dynamically enforce that an immutable delayed var/let isn't reset after it's been initialized. It also communicates intent; as I mentioned to Matthew in another subthread, </span></div></blockquote></div><br class=""><div class="">Sorry, trailed off here. As I mentioned to Matthew in another subthread, the implementation of `delayed` could interact with the SIL diagnostic passes so that you still get DI errors in obviously wrong cases, like using the property before you `initialize` it, initializing it more than once, etc.</div><div class=""><br class=""></div><div class="">-Joe</div></body></html>