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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>I think I might found a solution that will satisfy generic protocols and not break the system.</p>
<p>The generics manifesto shows two features that are requested from generic protocols.</p>
<p>The first feature is needed to reuse the same protocol multiple types like <code>struct A : Proto<B>, Proto<C></code>.</p>
<p>With SE–0142 we can actually achieve this behavior by creating new protocols and set a subset of the associated types from its parent super protocol.</p>
<p>Now we can use this trick to solve the problem from above and create two new protocols and use them as we previously wanted <code>struct A : ProtoB, ProtoC</code>. While this is great and solves my issue I’d like to pitch a shortcut for this.</p>
<p>Protocols with associated types are kinda generic, but they still need SE–0142 to specify all the associated types.</p>
<p>How about making all protocols that contain associated types to also have a shortcut generic protocol that specifies all the associated type in its generic parameter list?</p>
<p>Some first bikeshedding:</p>
<pre><code class="swift">protocol MyStringCollection : Collecntion where Iterator.Element == String, Index == Int {}
protocol Collection<ElementType, IndexType> : Collection {
typealias Iterator.Element = ElementType
typealias Index = IndexType
}
</code></pre>
<p>But instead of creating these types by yourself, the compiler would autogenerate these for any protocol that have a list of associated types. To prevent collision between protocol names like <code>Collection</code> vs. <code>Collection<ParamList></code> one could automatically prefix the generated procols with <code>Generic</code>.</p>
<p><code>Collection</code> will generate <code>GenericCollection<Element, Index></code></p>
<p>This would be a huge shortcut for the feature introduced in SE–0142.</p>
<p>What does the community think about this idea? </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_1480752646835070976" 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 2. Dezember 2016 um 20:13:50, Charles Srstka (<a href="mailto:cocoadev@charlessoft.com">cocoadev@charlessoft.com</a>) schrieb:</p> <blockquote type="cite" class="clean_bq"><span><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div></div><div>
<title></title>
<blockquote type="cite" class="">On Dec 2, 2016, at 12:34 PM,
Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""></blockquote>
<div>
<blockquote type="cite" class=""><br class="Apple-interchange-newline">
<div class="">
<p style="margin: 15px 0px; -webkit-margin-before: 0px; font-family: Helvetica, Arial; font-size: 13px; 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="">I just overlooked that the subsection about generic
protocols was inside the<span class="Apple-converted-space"> </span><strong style="-webkit-margin-before: 0px;" class="">Unlikely</strong><span class="Apple-converted-space"> </span>section.</p>
<p style="margin: 15px 0px; font-family: Helvetica, Arial; font-size: 13px; 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="">The problem is that I need a way to refer to a function
with a specific name. Plus the connection type has to have a
specific API, like having a DispatchQueue and know the router
object if there is any (sounds like a protocol right?!). The
function reference should also keep the connection object alive
with a strong reference.<span class="Apple-converted-space"> </span></p>
<p style="margin: 15px 0px; font-family: Helvetica, Arial; font-size: 13px; 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=""><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal; -webkit-margin-before: 0px;" class="">associatedtype</code><span class="Apple-converted-space"> </span>does not solve that problem
for me.</p>
<p style="margin: 15px 0px; font-family: Helvetica, Arial; font-size: 13px; 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="">I clearly see that generic protocols overlap
with<span class="Apple-converted-space"> </span><code style="font-family: Menlo, Consolas, 'Liberation Mono', Courier, monospace; font-size: 10pt; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; background-color: rgb(248, 248, 248); color: inherit; border: 1px solid rgb(234, 234, 234); margin: 0px 2px; padding: 0px 5px; word-break: normal; word-wrap: normal; -webkit-margin-before: 0px;" class="">associatedtype</code><span class="Apple-converted-space"> </span>but couldn’t we find a
compromise here? For instance like Chris Lattner introduced generic
type aliases without the ability of constants.</p>
</div>
</blockquote>
</div>
<div class="">Why don’t we just use angle brackets to specify
associated types? Protocols aren’t using them for anything anyway.
Then you could:</div>
<div class=""><br class=""></div>
<div class="">if let someSequence as? Sequence<Iterator.Element
== Int> { // do something }</div>
<div class=""><br class=""></div>
<div class="">which would form a nice parallel to the syntax for
casting things to generic types.</div>
<div class=""><br class=""></div>
<div class="">Charles</div>
<div class=""><br class=""></div>
</div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>