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.error { color:#AA0000; }</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class="bloop_markdown"><p>Not true, we already stated a clear rule how existentials should work with class-requirements long time ago (don’t mind lowercased <code>any</code> here):</p>
<h3 id="nestedany...">Nested <code>any<...></code></h3>
<p>A nested <code>any<...></code> may declare a class or any-class constraint, even if its parent <code>any<...></code> contains a class or any-class constraint, or a sibling <code>any<...></code> constraint declares a class or any-class constraint. <strong><u>However, one of the classes must be a subclass of every other class declared within such constraints, or all the classes must be the same. This class, if it exists, is chosen as the <code>any<...></code> construct’s constraint.</u></strong></p>
<pre><code class="swift">// Can be any type that is a UITableView conforming to ProtocolA.
// UITableView is the most specific class, and it is a subclass of the other
// two classes.
let a : any<UIScrollView, any<UITableView, any<UIView, ProtocolA>>>
// REDUNDANT: could be banned by another proposal.
// Identical to any<ProtocolA, ProtocolB>
let b : any<any<ProtocolA, ProtocolB>>
// NOT ALLOWED: no class is a subclass of all the other classes. This cannot be
// satisfied by any type.
let c : any<NSObject, any<UIView, any<NSData, ProtocolA>>>
</code></pre>
<p>Using typealiases, it is possible for <code>any<...></code> existentials to be composed. This allows API requirements to be expressed in a more natural, modular way:</p>
<pre><code class="swift">// Any custom UIViewController that serves as a delegate for a table view.
typealias CustomTableViewController = any<UIViewController, UITableViewDataSource, UITableViewDelegate>
// Pull in the previous typealias and add more refined constraints.
typealias PiedPiperResultsViewController = any<CustomTableViewController, PiedPiperListViewController, PiedPiperDecompressorDelegate>
</code></pre>
<p>Any <code>any<...></code> containing nested <code>any<...></code>s can be conceptually ‘flattened’ and written as an equivalent <code>any<...></code> containing no nested <code>any<...></code> requirements. The two representations are exactly interchangeable.</p>
<hr>
<p>That said, your example won’t work just because <code>UIViewController</code> and <code>UIWindow</code> are not compatible. The whole class-requirement is not based on the base types of all provided classes, but checked their own relationship instead.</p>
<p></p></div><div class="bloop_original_html"><style>body{font-family:Helvetica,Arial;font-size:13px}</style><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <br> <div id="bloop_sign_1465940063150628096" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">-- <br>Adrian Zubarev<br>Sent with Airmail</div></div> <br><p class="airmail_on">Am 14. Juni 2016 um 21:25:31, L. Mihalkovic (<a href="mailto:laurent.mihalkovic@gmail.com">laurent.mihalkovic@gmail.com</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div><div style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; 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;">Which addresses the fact that nons of the proposals so far truly prevent absurde declarations like:</div><div style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; 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></div><div style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; 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;">Let v: Any< UIViewController, UIWindow, UITableViewDelegate></div><div style="color: rgb(0, 0, 0); font-family: 'helvetica Neue', helvetica; font-size: 14px; 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;">Let v:<span class="Apple-converted-space"> </span><span style="background-color: rgba(255, 255, 255, 0);">UIViewController & UIWindow & UITableViewDelegate</span></div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>