<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="">100% agree with everything. A custom operator is a good idea for operations that are actually frequent: once you learn what it means, it really helps reduce noise in code and improve readability. But forced unwrapping is something that's intended to be used sparsely.<div class=""><br class=""></div><div class=""><br class=""></div><div class="">Elviro<br class=""><div class=""><br class=""></div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">Il giorno 30 giu 2017, alle ore 10:15, Víctor Pimentel Rodríguez via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> ha scritto:</div><br class="Apple-interchange-newline"><div class=""><div dir="ltr" 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=""><div class="gmail_extra"><div class="gmail_quote">On Fri, Jun 30, 2017 at 7:24 AM, Brent Royal-Gordon via swift-evolution<span class="Apple-converted-space"> </span><span dir="ltr" class=""><<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>></span><span class="Apple-converted-space"> </span>wrote:<br class=""><blockquote class="gmail_quote" style="margin: 0px 0px 0px 0.8ex; border-left-width: 1px; border-left-style: solid; border-left-color: rgb(204, 204, 204); padding-left: 1ex;"><div style="word-wrap: break-word;" class=""><div class=""><div class="h5"><div class=""><blockquote type="cite" class=""><div class="">On Jun 27, 2017, at 10:16 AM, Erica Sadun via swift-evolution <<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>> wrote:</div><br class="m_-7157450599931287639Apple-interchange-newline"><div class=""><div style="word-wrap: break-word;" class=""><div class="">Using an operator to provide feedback on the context of a failed unwrap has become a commonly implemented approach in the Swift developer Community. What are your thoughts about adopting this widely-used operator into the standard library?</div><div class=""><br class=""></div><div class=""><font face="Menlo" class="">guard !lastItem.isEmpty else { return }</font></div><div class=""><font face="Menlo" class="">let lastItem = array.last !! "Array must be non-empty"</font></div><div class=""><br class=""></div><div class="">Details here: <a href="https://gist.github.com/erica/423e4b1c63b95c4c90338cdff4939a9b" target="_blank" class="">https://gist.github.com/<wbr class="">erica/<wbr class="">423e4b1c63b95c4c90338cdff4939a<wbr class="">9b</a></div><div class=""><br class=""></div><div class="">Thank you for your thoughtful feedback, -- E</div></div></div></blockquote><br class=""></div></div></div><div class="">Finally found a few minutes to read this thread.</div><div class=""><br class=""></div><div class="">I'm a big fan of the `Never`-based approach. (I was before, but I am more so now.) Here are the points I can see in its favor:</div><div class=""><br class=""></div><div class="">1. It is extremely clear about what's happening—`!!` is another random operator to learn, but `fatalError(_:)` or `preconditionFailure(_:)` are fairly self-explanatory, and `??` is something you might already be using.</div><div class=""><br class=""></div><div class="">2. It allows you to control the optimization behavior by using `fatalError`, `preconditionFailure`, or `assertionFailure` as desired.</div><div class=""><br class=""></div><div class="">3. If we later change `throw` from being a statement to being a `Never`-returning expression, you could use `throw` on the right-hand side of `??`.</div><div class=""><br class=""></div><div class="">4. It supports other `Never`-returning operations, like `abort()` or `exit(_:)` or your custom `usage()` function, on the right side of `??`.</div><div class=""><br class=""></div><div class=""><div class="">5. It supports file-and-line error reporting without having to add any new features; `!!` could not do this because an operator can't have extra, defaulted parameters to carry the file and line.</div><div class=""><br class=""></div></div><div class="">6. It harmonizes with the eventual idea of making `Never` a universal bottom type, but we don't actually have to implement that today, because we can just overload `??` for now.</div><div class=""><br class=""></div><div class="">Against these advantages, the only one I can see for `!!` is that it is terse. Terseness is good, especially for a feature which is competing with the single-character postfix `!` operator, but I can't help but be drawn to the flexibility and power of `??` with a `Never` expression on the right-hand side.</div></div></blockquote></div><div class=""><br class=""></div><div class="">+1 to everything.</div><div class=""><br class=""></div><div class="">If terseness is the only clear advantage of a new operator that is meant to be used sparsely, it's clear to me that the ?? Never form is better for the Swift community as a whole.</div><div class=""><br class=""></div>--<br class=""><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" class=""><div dir="ltr" style="font-size: 12.8px;" class=""><div style="font-size: 12.8px;" class=""></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><div class="gmail_extra">Víctor Pimentel</div></div><span 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; float: none; display: inline !important;" class="">_______________________________________________</span><br 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=""><span 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; float: none; display: inline !important;" class="">swift-evolution mailing list</span><br 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=""><a href="mailto:swift-evolution@swift.org" 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;" class="">swift-evolution@swift.org</a><br 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=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" 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;" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div><br class=""></div></div></body></html>