<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div>I agree this looks better when something is being returned. </div><div><br></div><div>What would it look like if the function returns nothing but can throw an error?</div><div><br></div><div>Brandon</div><div><br>On Jan 9, 2017, at 4:10 AM, Tyler Cloutier via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br><br></div><blockquote type="cite"><div><meta http-equiv="Content-Type" content="text/html charset=utf-8"><br class=""><div><blockquote type="cite" class=""><div class="">On Dec 26, 2016, at 2:55 PM, Dave Abrahams 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=""><br 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=""><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="">on Mon Dec 26 2016, thislooksfun <</span><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><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="">> wrote:</span><br 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=""><br 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=""><blockquote type="cite" 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="">Hello Swifters,<br class=""><br class="">I've been writing a lot more Swift code recently, and I have found<br class="">that the default placement of the 'throws' declaration is often<br class="">confusing, especially to those of us switching from languages where<br class="">the type of errors thrown is explicitly defined (like Java)<br class=""><br class="">For example,<br class="">// This is pretty clear, this can throw an error<br class="">func foo() throws<br class="">{ ... }<br class=""><br class="">// Also pretty clear, this returns a String<br class="">func bar() -> String<br class="">{ ... }<br class=""><br class="">// Confusing. Does this throw a String? Does it return a String? Does it do both?<br class="">// I personally keep reading this as 'this can throw a String'<br class="">func baz() throws -> String<br class=""><br class="">// Equivalent code in Java (not a model, just for clarification of why the above is confusing)<br class="">String baz() throws StringFormatException<br class="">I therefore suggest either tweaking the syntax around, or moving, the<br class="">`throws` keyword to avoid this confusion.<br class=""><br class="">Some ideas I've had:<br class="">// Add a comma to separate them<br class="">func baz() throws, -> String<br class=""><br class="">// Move `throws` to the end<br class="">func baz() -> String throws<br class=""></blockquote><br 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=""><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="">I agree that reads much better.</span><br 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></blockquote><div><br class=""></div><div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">func</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> baz() -> (</span><span style="color: rgb(0, 175, 202); font-variant-ligatures: no-common-ligatures;" class="">String</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> | </span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">throws</span><span style="font-variant-ligatures: no-common-ligatures;" class="">)</span></div></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><div style="font-family: Helvetica; font-size: 12px;" class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">func</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> baz() -> (</span><span style="color: rgb(0, 175, 202); font-variant-ligatures: no-common-ligatures;" class="">String</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> | </span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">throws: BazError</span><span style="font-variant-ligatures: no-common-ligatures;" class="">)</span></div></div><div style="margin: 0px; line-height: normal;" class=""></div></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><div style="margin: 0px; line-height: normal;" class=""><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">let</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> x: (</span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">_</span><span style="color: rgb(255, 255, 255); font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures;" class="">a: </span><span style="color: rgb(0, 175, 202); font-variant-ligatures: no-common-ligatures;" class="">Int</span><span style="font-variant-ligatures: no-common-ligatures;" class="">) -> (</span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">throws</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> | (</span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">_</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> b: Float) -> (</span><span style="color: rgb(194, 52, 155); font-variant-ligatures: no-common-ligatures;" class="">throws</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> | Double))</span></div><div style="margin: 0px; line-height: normal;" class=""><br class=""></div></div><div class="">Now where getting somewhere. Somewhere weird, to be sure… but somewhere.</div></div><div><br class=""></div><br class=""><blockquote type="cite" class=""><div class=""><br 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=""><blockquote type="cite" 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="">// Change it to a prefix modifier (like `mutating`)<br class="">throwing func baz() -> String<br class="">I'm still not sold on any of the above syntaxes, but I would love to hear your feedback.<br class=""><br class="">This would affect existing code, but it would be a fairly small change<br class="">that would result in very large readability improvements, especially<br class="">for newcomers, and especially for those coming for a language such as<br class="">Java.<br class=""><br class="">-thislooksfun (tlf)<br class=""><br class="">_______________________________________________<br class="">swift-evolution mailing list<br class=""><a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a><br class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class=""><br class=""></blockquote><br 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=""><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="">--<span class="Apple-converted-space"> </span></span><br 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=""><span style="font-family: Helvetica; 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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></blockquote><blockquote type="cite"><div><span>_______________________________________________</span><br><span>swift-evolution mailing list</span><br><span><a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a></span><br><span><a href="https://lists.swift.org/mailman/listinfo/swift-evolution">https://lists.swift.org/mailman/listinfo/swift-evolution</a></span><br></div></blockquote></body></html>