<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 Jan 11, 2016, at 12:49 PM, Joe Groff <<a href="mailto:jgroff@apple.com" class="">jgroff@apple.com</a>> wrote:</div><br class="Apple-interchange-newline"><div 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="">SGTM. A few points I didn't see addressed from the last thread:</span><div 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-stroke-width: 0px;"><br class=""></div><div 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-stroke-width: 0px;">- Do we need the '_' representing unlabeled arguments? 'foo(:bar:)' should be workable, as in ObjC.</div></div></blockquote><div><br class=""></div><div>We discussed this a looooong while back and decided that we wanted the ‘_’ to emphasize that there is an argument there. The difference between “<font face="Menlo" class="">foo(:bar:)</font>” and “<font face="Menlo" class="">foo(bar:)</font>” is barely visible.</div><br class=""><blockquote type="cite" class=""><div class=""><div 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-stroke-width: 0px;">- How do references to defaulted or variadic arguments work? Do you have to reference their labels completely in declared order, or could you refer to 'func foo(x: Int = 5, y: String = "")' as 'foo(y:x:)', 'foo(x:)', and/or 'foo(y:)' as well?</div></div></blockquote><div><br class=""></div>You have to reference their labels completely in declared order; that’s the name of the method.</div><div><br class=""></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>- Doug</div><div><br class=""><blockquote type="cite" class=""><div class=""><div 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-stroke-width: 0px;"><br class=""></div><div 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-stroke-width: 0px;">-Joe</div><div 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-stroke-width: 0px;"><br class=""><div class=""><blockquote type="cite" class=""><div class="">On Jan 11, 2016, at 11:03 AM, Douglas Gregor 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=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Hi all,<div class=""><br class=""></div><div class="">I’ve updated and simplified my “Generalized Naming for Any Function” proposal to only deal with naming functions with argument labels, and dropping the back-ticks. Comments welcome! Proposal is here</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span><a href="https://github.com/DougGregor/swift-evolution/blob/generalized-naming/proposals/0000-generalized-naming.md" class="">https://github.com/DougGregor/swift-evolution/blob/generalized-naming/proposals/0000-generalized-naming.md</a></div><div class=""><br class=""></div><div class="">and inline:</div><div class=""><br class=""></div><div class=""><h1 class="" style="box-sizing: border-box; font-size: 2.25em; margin-right: 0px; margin-bottom: 16px; margin-left: 0px; line-height: 1.2; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255); margin-top: 0px !important;">Naming Functions with Argument Labels</h1><ul class="" style="box-sizing: border-box; padding: 0px 0px 0px 2em; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><li class="" style="box-sizing: border-box;">Proposal: <a href="https://github.com/apple/swift-evolution/blob/master/proposals/0000-generalized-naming.md" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">SE-NNNN</a></li><li class="" style="box-sizing: border-box;">Author(s): <a href="https://github.com/DougGregor" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">Doug Gregor</a></li><li class="" style="box-sizing: border-box;">Status: <strong class="" style="box-sizing: border-box;">Awaiting Review</strong></li><li class="" style="box-sizing: border-box;">Review manager: TBD</li></ul><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-introduction" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#introduction" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Introduction</h2><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">Swift includes support for first-class functions, such that any function (or method) can be placed into a value of function type. However, when specifying the name of a function, one can only provide the base name, (e.g., <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">insertSubview</code>) without the argument labels. For overloaded functions, this means that one must disambiguate based on type information, which is awkward and verbose. This proposal allwos one </p><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">it is not possible to specifically name every function that is part of a Swift program---one cannot provide the argument labels when naming a function, nor are property and subscript getters and setters referenceable. This proposal introduces a general syntax that allows one to name anything that is a function within Swift in an extensible manner.</p><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">Swift-evolution thread: The first draft of this proposal was discussed <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151221/004555.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">here</a>. It included support for naming getters/setters (separately brought up by Michael Henson <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151207/002168.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">here</a>, continued <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151214/002203.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">here</a>). Joe Groff <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151221/004579.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">convinced</a> me that lenses are a better approach for working with getters/setters, so I've dropped them from this version of the proposal.</p><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-motivation" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#motivation" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Motivation</h2><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">It's fairly common in Swift for multiple functions or methods to have the same "base name", but be distinguished by parameter labels. For example, <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">UIView</code> has three methods with the same base name <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">insertSubview</code>:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">extension</span> UIView {
<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">func</span> <span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163);">insertSubview</span>(view: UIView, at <span class="pl-smi" style="box-sizing: border-box;">index</span>: <span class="pl-c1" style="box-sizing: border-box; color: rgb(0, 134, 179);">Int</span>)
<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">func</span> <span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163);">insertSubview</span>(view: UIView, aboveSubview <span class="pl-smi" style="box-sizing: border-box;">siblingSubview</span>: UIView)
<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">func</span> <span class="pl-en" style="box-sizing: border-box; color: rgb(121, 93, 163);">insertSubview</span>(view: UIView, belowSubview <span class="pl-smi" style="box-sizing: border-box;">siblingSubview</span>: UIView)
}</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">When calling these methods, the argument labels distinguish the different methods, e.g.,</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;">someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(view, at: <span class="pl-c1" style="box-sizing: border-box; color: rgb(0, 134, 179);">3</span>)
someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(view, aboveSubview: otherView)
someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(view, belowSubview: otherView)</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">However, when referencing the function to create a function value, one cannot provide the labels:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview <span class="pl-c" style="box-sizing: border-box; color: rgb(150, 152, 150);">// ambiguous: could be any of the three methods</span></pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">In some cases, it is possible to use type annotations to disambiguate:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn: (UIView, <span class="pl-c1" style="box-sizing: border-box; color: rgb(0, 134, 179);">Int</span>) <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview <span class="pl-c" style="box-sizing: border-box; color: rgb(150, 152, 150);">// ok: uses insertSubview(_:at:)</span>
<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn: (UIView, UIView) <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview <span class="pl-c" style="box-sizing: border-box; color: rgb(150, 152, 150);">// error: still ambiguous!</span></pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">To resolve the latter case, one must fall back to creating a closure:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn: (UIView, UIView) <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> { view, otherView <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">in</span>
button<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(view, aboveSubview: otherView)
}</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">which is painfully tedious. </p><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">One additional bit of motivation: Swift should probably get some way to ask for the Objective-C selector for a given method (rather than writing a string literal). The argument to such an operation would likely be a reference to a method, which would benefit from being able to name any method, including getters and setters.</p><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-proposed-solution" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#proposed-solution" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Proposed solution</h2><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">I propose to extend function naming to allow compound Swift names (e.g., <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">insertSubview(_:aboveSubview:)</code>) anywhere a name can occur. Specifically,</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(_:at:)
<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> fn1 <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> someView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(_:aboveSubview:)</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">The same syntax can also refer to initializers, e.g.,</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> buttonFactory <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> UIButton<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">init</span>(type:)</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">The "produce the Objective-C selector for the given method" operation will be the subject of a separate proposal. However, here is one possibility that illustrations how it uses the proposed syntax here:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;"><span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">let</span> getter <span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">=</span> Selector(NSDictionary<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(_:aboveSubview:)) <span class="pl-c" style="box-sizing: border-box; color: rgb(150, 152, 150);">// produces insertSubview:aboveSubview:.</span></pre></div><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-detailed-design" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#detailed-design" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Detailed Design</h2><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">Grammatically, the <em class="" style="box-sizing: border-box;">primary-expression</em> grammar will change from:</p><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 16px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; color: rgb(51, 51, 51);"><code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; border: 0px; display: inline; line-height: inherit; word-wrap: normal;">primary-expression -> identifier generic-argument-clause[opt]
</code></pre><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">to:</p><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 16px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; color: rgb(51, 51, 51);"><code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; border: 0px; display: inline; line-height: inherit; word-wrap: normal;">primary-expression -> unqualified-name generic-argument-clause[opt]
unqualified-name -> identifier
| identifier '(' ((identifier | '_') ':')+ ')'
</code></pre><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">Within the parentheses, the use of "+" is important, because it disambiguates:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;">f()</pre></div><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">as a call to <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">f</code> rather than a reference to an <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">f</code> with no arguments. Zero-argument function references will still require disambiguation via contextual type information.</p><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-impact-on-existing-code" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#impact-on-existing-code" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Impact on existing code</h2><p class="" style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255);">This is a purely additive feature that has no impact on existing code.</p><h2 class="" style="box-sizing: border-box; margin-top: 1em; margin-bottom: 16px; line-height: 1.225; font-size: 1.75em; padding-bottom: 0.3em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: rgb(238, 238, 238); color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; background-color: rgb(255, 255, 255);"><a id="user-content-alternatives-considered" class="anchor" href="https://github.com/DougGregor/swift-evolution/tree/generalized-naming#alternatives-considered" aria-hidden="true" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none; display: inline-block; padding-right: 2px; margin-left: -18px; line-height: 1;"><span class="octicon octicon-link" style="box-sizing: border-box; font-weight: normal; font-size: 16px; line-height: 1; font-family: octicons; display: inline-block; text-rendering: auto; -webkit-font-smoothing: antialiased; -webkit-user-select: none; vertical-align: middle; visibility: hidden;"></span></a>Alternatives considered</h2><ul class="" style="box-sizing: border-box; padding: 0px 0px 0px 2em; margin-top: 0px; color: rgb(51, 51, 51); font-family: 'Helvetica Neue', Helvetica, 'Segoe UI', Arial, freesans, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; font-size: 16px; background-color: rgb(255, 255, 255); margin-bottom: 0px !important;"><li class="" style="box-sizing: border-box;"><p class="" style="box-sizing: border-box; margin-top: 16px; margin-bottom: 16px;">Joe Groff <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151214/003008.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">notes</a> that <em class="" style="box-sizing: border-box;">lenses</em> are a better solution than manually retrieving getter/setter functions when the intent is to actually operate on the properties.</p></li><li class="" style="box-sizing: border-box;"><p class="" style="box-sizing: border-box; margin-top: 16px; margin-bottom: 16px;">Bartlomiej Cichosz <a href="https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20151228/004739.html" class="" style="box-sizing: border-box; background-color: transparent; color: rgb(64, 120, 192); text-decoration: none;">suggests</a> a general partial application syntax using <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">_</code> as a placeholder, e.g.,</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px;"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;">aGameView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(_, aboveSubview: playingSurfaceView)</pre></div><p class="" style="box-sizing: border-box; margin-top: 16px; margin-bottom: 16px;">When all arguments are <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">_</code>, this provides the ability to name any method:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px;"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;">aGameView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview(_, aboveSubview: _)</pre></div><p class="" style="box-sizing: border-box; margin-top: 16px; margin-bottom: 16px;">I decided not to go with this because I don't believe we need such a general partial application syntax in Swift. Closures using the $ names are nearly as concise, and eliminate any questions about how the <code class="" style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; padding: 0.2em 0px; margin: 0px; background-color: rgba(0, 0, 0, 0.0392157); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px;">_</code> placeholder maps to an argument of the partially-applied function:</p><div class="highlight highlight-source-swift" style="box-sizing: border-box; margin-bottom: 16px;"><pre class="" style="box-sizing: border-box; overflow: auto; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 14px; margin-top: 0px; margin-bottom: 0px; line-height: 1.45; padding: 16px; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-wrap: normal; word-break: normal;">{ aGameView<span class="pl-k" style="box-sizing: border-box; color: rgb(167, 29, 93);">.</span>insertSubview($<span class="pl-c1" style="box-sizing: border-box; color: rgb(0, 134, 179);">0</span>, aboveSubview: playingSurfaceView) }</pre></div></li></ul><div class=""><br class=""></div></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>- Doug</div><div class=""><br class=""></div><img src="https://u2002410.ct.sendgrid.net/wf/open?upn=RoDF4MveSEMYBIqIJA6ub1g8cOZ-2BVYvqV-2FqygPhjPn9XJxSqx-2Fq4l57S7RKxFAbYN5ljovzwFw1UNZfKJSNMPy9bzmZOWjdG6h-2BCnmawhWQj8caMAYp5iywtXCIDeqQkc68DYWjfAw0tSOtiPcX-2BnKMXM3AYhx9LzJ-2FMHJVxUZqJpIiIkJv6O-2F1KBJDI1XTTKN7fggZLNZFLV1Wz-2FYncowiPN3az5-2FEJI2CVf4gzI-2B4-3D" alt="" width="1" height="1" border="0" class="" style="height: 1px !important; width: 1px !important; border-width: 0px !important; margin: 0px !important; padding: 0px !important;"></div>_______________________________________________<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" class="">https://lists.swift.org/mailman/listinfo/swift-evolution</a></div></blockquote></div></div></div></blockquote></div><br class=""></body></html>