<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="">Currently it doesn’t seem possible to define a property or variable of a specific class that also implements one or more protocols.</div><div class="">Take as an example the following definition from Objective C:</div><div class=""><br class=""></div><div class="">NSManagedObject<NSCoding, Task>* someObject;</div><div class=""><br class=""></div><div class="">To my knowledge, currently it is only possible to define multiple protocols only:</div><div class=""><br class=""></div><div class="">var object : protocol<NSCoding, Task></div><div class=""><br class=""></div><div class="">However, given the first example, sometimes it is not possible to restrict to protocols only. This becomes especially cumbersome, if you would need to cast down to such a construct within a single method and perform several steps which would require all those type information:</div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class=""><br class=""></span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">func</span> doSomething(object: <span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">AnyObject</span>) {</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">if</span> <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">let</span> managedObject = object <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">as</span>? <span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NSManagedObject</span> {</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span>// Do core data related stuff</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> }</div><p style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; min-height: 13px;" class=""> <br class="webkit-block-placeholder"></p><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">if</span> <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">let</span> task = object <span style="font-variant-ligatures: no-common-ligatures; color: #bb2ca2" class="">as</span>? <span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">Task</span> {</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #000000" class=""> </span>// Do task related stuff</div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""> } </div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class="">}</div></div><div class=""><br class=""></div><div class="">In this case you now have managedObject and task though you operate on the same object. Also it is not (easily) possible to interleave actions of those two.</div><div class=""><br class=""></div><div class="">My first idea here would be to introduce an Objective C like style of type naming. This also has the benefit, that it is perfectly clear, whether a type name refers to a class or a protocol (without first having to check it).</div><div class="">The downside, of course, is that protocol type variables would become something like Any<MyProtocol></div><div class=""><br class=""></div><div class="">Any other ideas are welcome, but the initial problem still stands and should be addressed.</div></body></html>