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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>Doesn’t this imply more performance cost? Don’t get me wrong but the value here is not fixed and computed all over again which might waste resources if the calculation is complicated. Sure we could build some workarounds here and there, but the codebase won’t get any prettier after that.</p>
<p>Another though is that enums just need stored properties to solve the main problem here nicely. I don’t remember what the outcome of that talk was back then. I’ll search for that conversation soon. </p>
<p>Anyways, thank you Joe for showing us the possible workaround.</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_1475603717286669056" 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 4. Oktober 2016 um 19:52:11, Joe Groff (<a href="mailto:jgroff@apple.com">jgroff@apple.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>
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Oct 3, 2016, at 12:50 PM, Adrian Zubarev 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="bloop_markdown" style="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; background-color: rgb(254, 254, 254);">
<p style="margin: 15px 0px; -webkit-margin-before: 0px;" class="">
Hi there,</p>
<p style="margin: 15px 0px;" class="">I’m interested if this idea
has some potential future in Swift or not.</p>
<p style="margin: 15px 0px;" class="">Currently RawRepresentable
enums accept only a subset of literal types like String, Character
and the Integer family (<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="">enum Name : String { … }</code>).</p>
<p style="margin: 15px 0px;" class="">Sometimes this is not enough
for my use-case and I wish I could feed my enums with other
Hashable types!</p>
<p style="margin: 15px 0px;" class="">As a workaround I can create
a custom struct or even a class and conform it to<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="">RawRepresentable</code><span class="Apple-converted-space"> </span>and fake an enum with some
static variables (similar to what is done 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;" class="">OptionSet</code><span class="Apple-converted-space"> </span>types).</p>
<div class=""><br class=""></div>
</div>
</div>
</blockquote>
<div><br class=""></div>
The literal type constraint only affects the sugar syntax using the
': String' and 'case X = 1' syntax. If you write an enum's
conformance explicitly, you can use any raw type you like:</div>
<div><br class=""></div>
<div>enum Test: RawRepresentable {</div>
<div> case something, nothing</div>
<div><br class=""></div>
<div> init?(rawValue: A) {</div>
<div> switch rawValue.value {</div>
<div> case "something": self = .something</div>
<div> case "nothing": self = .nothing</div>
<div> default: return nil</div>
<div> }</div>
<div> }</div>
<div><br class=""></div>
<div> var rawValue: A {</div>
<div> switch self {</div>
<div> case .something: return A(value:
"something")</div>
<div> case .nothing: return A(value: "nothing")</div>
<div> }</div>
<div> }</div>
<div>}</div>
<div><br class=""></div>
<div>though it's up to you at this point to guarantee the 1:1
correspondence between raw values and enum values that
RawRepresentable assumes.</div>
<div><br class=""></div>
<div>-Joe<br class="">
<blockquote type="cite" class="">
<div class="">
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<p style="margin: 15px 0px;" class="">The problem there is that I
cannot use the same switch pattern matching like with enums. I’d
wish either enums could accept Hashable types (maybe with some
restriction) or the existence on a protocol to build custom
enum-like types with strucs/classes and use the same switch pattern
matching.</p>
<pre style="margin: 15px 0px; 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(204, 204, 204); overflow: auto; padding: 4px 8px; word-break: normal; word-wrap: normal;" class=""><code class="swift" 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: 0px; margin: 0px; padding: 0px; word-break: normal; word-wrap: normal; -webkit-margin-before: 0px;">struct A : Hashable { /* implement everything */ }
// Variant 1:
enum Test : A {
case something = A(rawValue: A(value: "something"))
case nothing = A(rawValue: A(value: "nothing"))
}
// Variant 2:
protocol SomeFancyName : RawRepresentable { … }
struct Test : SomeFancyName {
let rawValue: A
init?(rawValue: A) {
// Implement + reject unwanted `A`s
}
static let something = A(rawValue: A(value: "something"))
static let nothing = A(rawValue: A(value: "nothing"))
}
let value = Test.something
switch value {
case .something:
// handle
case .nothing:
// handle
// Because of `SomeFancyName` the switch can use enum-like pattern matching + does not need the `default` case when all cases are present
}
</code></pre>
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<div class="bloop_original_html" style="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; background-color: rgb(254, 254, 254);">
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<br class="">
<div id="bloop_sign_1475522853802483200" class="bloop_sign">
<div style="font-family: helvetica, arial; font-size: 13px;" class="">-- <br class="">
Adrian Zubarev<br class="">
Sent with Airmail</div>
</div>
</div>
<div class="bloop_markdown" style="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; background-color: rgb(254, 254, 254);">
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<span style="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; background-color: rgb(254, 254, 254); float: none; display: inline !important;" class="">_______________________________________________</span><br style="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; background-color: rgb(254, 254, 254);" class="">
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</blockquote>
</div>
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</div></div></span></blockquote></div><div class="bloop_markdown"><p></p></div></body></html>