<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=""><div class="">I thought about including <font face="Menlo" color="#ff4013" class="">@deprecated</font> as an alternative, but it needs some addition tweaking outside of<font color="#ff4013" class=""> <font face="Menlo" class="">@unavailable</font></font> and <font face="Menlo" color="#ff4013" class="">@restricted</font>.</div><div class=""><br class=""></div><div class="">For example, would arguments like <font face="Menlo" color="#ff4013" class="">introduced</font> and <font face="Menlo" color="#ff4013" class="">obsoleted</font> still be available for use, or would they need to be separated out? </div><div class=""><br class=""></div><div class=""><font color="#ff4013" face="Menlo" class="">@introduced(iOS 9.0)</font></div><div class=""><font color="#ff4013" face="Menlo" class="">@deprecated(iOS 9.1, message="Use a.n.other protocol")</font></div><div class=""><font color="#ff4013" face="Menlo" class="">@obsoleted(iOS 9.2, message="Use a.n.other </font><span style="color: rgb(255, 64, 19); font-family: Menlo;" class="">protocol</span><font color="#ff4013" face="Menlo" class="">")</font></div><div class=""><font face="Menlo" class="">protocol MyProtocol { }</font></div><div class=""><br class=""></div><div class="">I think <font color="#ff4013" class=""><font face="Menlo" class="">@unavailable</font></font> and <font face="Menlo" color="#ff4013" class="">@restricted </font>lend themselves to the existing syntax.</div><div class=""><br class=""></div><div class="">Stuart </div><br class=""><div><blockquote type="cite" class=""><div class="">On 26 May 2016, at 21:48, Charlie Monroe <<a href="mailto:charlie@charliemonroe.net" class="">charlie@charliemonroe.net</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=utf-8" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">With the alternatives, I'd mention @deprecated as well.<div class=""><br class=""></div><div class="">Charlie<br class=""><div class="">
</div>
<br class=""><div class=""><blockquote type="cite" class=""><div class="">On May 26, 2016, at 3:25 PM, Stuart Breckenridge 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 style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><h1 id="addanrestricteddeclarationattribute" style="text-align: left; box-sizing: border-box; font-size: calc(1.2777777777777777rem); margin: 0px 0px calc(3.3333333333333335rem); line-height: calc(1.3043478260869565); text-transform: uppercase; letter-spacing: 0.5px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">ADD AN @RESTRICTED DECLARATION ATTRIBUTE</h1><ul style="box-sizing: border-box; padding-left: 1.5rem; margin: calc(1.6666666666666667rem) auto 0px; list-style: none; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><li style="box-sizing: border-box;" class="">Proposal: SE-NNNN</li><li style="box-sizing: border-box;" class="">Author: Stuart Breckenridge</li><li style="box-sizing: border-box;" class="">Status: DRAFT</li><li style="box-sizing: border-box;" class="">Review Manager: TBD</li></ul><h2 id="introduction" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Introduction</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Adapted from the Swift 2.2 Programming Guide:</div><blockquote style="box-sizing: border-box; margin: calc(1.6666666666666667rem) calc(-0.8888888888888888rem) 0px; padding-left: calc(2.2222222222222223rem); padding-right: calc(2.2222222222222223rem); font-style: italic; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px;" class="">The <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> attribute indicates a declaration’s life cycle relative to certain platforms and operating systems. Today’s functionality allows you to add multiple <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> attributes on a declaration to specify its availability on different platforms.</div></blockquote><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">In a related Swift Evolution discussion examining the <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> attribute, it was confirmed that there is currently no way to limit availability to specific platform without using the long form approach.</div><h2 id="motivation" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Motivation</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">When a declaration is only available on a certain platform, it requires multiple <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> attributes to restrict its availability to that platform. Consider the following example using <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">SLServiceType</code> like constants:</div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">@available(iOS, unavailable)
@available(tvOS, unavailable)
@available(watchOS, unavailable)
@available(OSX 10.8, *)
case LinkedIn = "com.apple.social.linkedin"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">The compiler will only use an <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> attribute when the attribute specifies a platform that matches the current target platform. The implication being that if the target platform isn’t specified, then the attribute defaults to available.</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Thus, while it is clear that the above is restricting availability to OS X 10.8 and later, it is verbose and <span style="box-sizing: border-box; font-weight: 600;" class="">can be simplified</span>.</div><h2 id="proposal" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Proposal</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Implement an <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> attribute which is the inverse of <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code>. The effect would be that the compiler would use <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> to limit the declaration to be available on the platform(s) specified in the attribute. Similar to <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code>, multiple <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> attributes can be added to a declaration. </div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Therefore, where <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> attribute(s) are present and target platform <em style="box-sizing: border-box;" class="">is not</em> specified, the declaration is not available on the unspecified target platform. In addition, where a <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> attribute has been applied to a declaration, it should not be commingled with <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> on the same declaration (it would lead to intense confusion).</div><h2 id="design" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Design</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">From a syntax perspective, it would follow <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code>:</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">@restricted(<code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">platform name</code> <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">version number</code>, *)</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">or</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">@restricted(<code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">platform name</code>, <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">introduced=version number</code>)</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Similarly, all <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> arguments would be available to <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code>. </div><h3 id="examples" style="text-align: left; box-sizing: border-box; margin-top: calc(1.6666666666666667rem); font-size: 1rem; margin-bottom: 0px; line-height: calc(1.6666666666666667); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Examples</h3><div class=""><br class=""></div><div style="box-sizing: border-box; margin: 0px auto; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Using the previous example, instead of using <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code> to specify unavailability, we use <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> to scope the declarations availability:</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><em style="box-sizing: border-box;" class="">Single Platform Restriction</em></div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">@restricted(OSX 10.8, *)
case LinkedIn = "com.apple.social.linkedin"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Effect: only available on OS X 10.8 or newer.</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><em style="box-sizing: border-box;" class="">Multiple Platform Restriction</em></div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">@restricted(OSX 10.8, iOS 9.4, *)
case LinkedIn = "com.apple.social.linkedin"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Effect: Available on OSX 10.8 or newer, and iOS 9.4 or newer.</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><em style="box-sizing: border-box;" class="">Restricted within Version Bounds</em></div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">@restricted(OSX, introduced=10.8, deprecated=10.10, obsoleted=10.11, message="No longer available.")
case LinkedIn = "com.apple.social.linkedin"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Effect: Available on OS X from 10.8 through 10.11 only.</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><em style="box-sizing: border-box;" class="">Restricted with Renamed Case</em></div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">// Initial Release
@restricted(OSX 10.10, *)
case TencentWeibo = "com.apple.social.tencentweibo"
// Second Release
@restricted(OSX, introduced=10.10, deprecated=10.11, renamed="Weibo")
case TencentWeibo = "com.apple.social.tencentweibo"
@restricted(OSX 10.11) case Weibo = "com.apple.social.weibo"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Effect: Initial release case is restricted to 10.10 and newer; second release has the original case deprecated from 10.11, with a new case introduced which is available on OS X 10.11 and newer only. </div><h2 id="benefitsimpactonexistingcode" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Benefits & Impact on existing code</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> has the benefit of reducing the amount code while maintaining clarity of purpose: it is obvious based on the attribute name what the intent is. </div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code> is purely additive, and therefore has no impact on existing code that makes use of <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code>. </div><h2 id="alternatives" style="text-align: left; box-sizing: border-box; margin-top: calc(3.3333333333333335rem); margin-bottom: calc(1.6666666666666667rem); font-size: calc(1.1666666666666667rem); line-height: calc(1.4285714285714286); color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif;" class="">Alternatives</h2><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">An alternative, though not a strict replacement of <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code>, could be to extract the <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">unavailable</code>argument and use it as an attribute (<code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@unavailable</code>). In use:</div><pre style="box-sizing: border-box; overflow: hidden; font-family: monospace, monospace; font-size: 14px; border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 1rem; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26);" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; padding: 0px;" class="">@available(OSX 10.8, *)
@unavailable(iOS, *)
case LinkedIn = "com.apple.social.linkedin"
</code></pre><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">Effect: Available on OS X but not iOS.</div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class=""><code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@unavailable</code> is worthy of further discussion as using an <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">unavailable</code> argument inside an <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@available</code>attribute seems counterintuitive. </div><div style="box-sizing: border-box; margin: calc(1.6666666666666667rem) auto 0px; color: rgb(26, 26, 26); font-family: NittiGrotesk, Keyboard, sans-serif; font-size: 14px;" class="">However, this proposal is limited to the consideration of <code style="box-sizing: border-box; font-family: NittiPro, Keyboard, monospace; font-size: calc(0.8333333333333334em); border-top-left-radius: 2px; border-top-right-radius: 2px; border-bottom-right-radius: 2px; border-bottom-left-radius: 2px; white-space: pre-wrap; background-color: rgb(230, 230, 230); padding: 0.1667em 0.3334em 0.25em;" class="">@restricted</code>.</div></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><br class=""></div></blockquote></div><br class=""></div></div></div></blockquote></div><br class=""></body></html>