<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="">"<span style="font-family: Helvetica, Arial; font-size: 13px; background-color: rgb(254, 254, 254);" class="">you can pass an autoclosure to an autoclosure</span><font face="Helvetica, Arial" size="2" class="">”</font><div class=""><font face="Helvetica, Arial" size="2" class=""><span style="background-color: rgb(254, 254, 254);" class=""><br class=""></span></font></div><div class=""><font face="Helvetica, Arial" size="2" class=""><span style="background-color: rgb(254, 254, 254);" class="">This is very surprising to me! I think that should be an error… When I write an argument of type `@autoclosure () -> T`, only arguments of type `T` ought to be accepted.</span></font></div><div class=""><font face="Helvetica, Arial" size="2" class=""><span style="background-color: rgb(254, 254, 254);" class=""><br class=""></span></font><div><blockquote type="cite" class=""><div class="">On Jul 1, 2017, at 3:50 PM, Adrian Zubarev <<a href="mailto:adrian.zubarev@devandartist.com" class="">adrian.zubarev@devandartist.com</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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><p style="margin: 15px 0px; -webkit-margin-before: 0px;" class="">It’s not about whether I should use these like this or not. It’s about that you can pass an autoclosure to an autoclosure (where the metatype is the same as a normal closure), but you cannot pass a normal closure to an autoclosure.<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="">@escaping</code><span class="Apple-converted-space"> </span>making things even worse. When using<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="">Void</code><span class="Apple-converted-space"> </span>as a return type Xcode will provide you an additional completion option which only will result in an error!</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 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;" class="">func foo(_: @autoclosure () -> Void) { }
func bar(_ test: @autoclosure () -> Void) {
foo(test) // works
}
func baz(_ test: @autoclosure @escaping () -> Void) {
print(type(of: test)) // prints `() -> ()`
foo(test) // error because it's `@escaping`
}
let closure: () -> Void = {}
bar(())
bar(closure) // error
// Suggested autocompletion by Xcode which results in an error
bar {
<#code#>
}
</code></pre><p style="margin: 15px 0px;" class="">Long story short autoclosure is bugged and deserves this fix.</p><hr style="height: 0.2em; border: 0px; color: rgb(204, 204, 204); background-color: rgb(204, 204, 204); display: inherit;" class=""><p style="margin: 15px 0px;" class="">Here a few examples where I’m using the mentioned non-generic extension instead of an if statement:</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 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;" class="">self.shouldPop.whenTrue(execute: self.toView.isUserInteractionEnabled = false)
($0 == .end).whenTrue(execute: completion)
(!option.isInteractive).whenTrue(execute: sendEvents)
</code></pre><p style="margin: 15px 0px;" class="">There are other cases where I’d use it, but I cannot because the generic autoclosure function simply does not work as I’d expect it to work:</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 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;" class="">@discardableReuslt
func whenTrue<T>(execute closure: @autoclosure () -> T) -> T? {
if self { return closure() }
return nil
}
</code></pre><div style="margin: 15px 0px;" class=""><br class="webkit-block-placeholder"></div></div><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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><div id="bloop_customfont" style="font-family: Helvetica, Arial; font-size: 13px; margin: 0px;" class=""><br class=""></div><br class=""><div id="bloop_sign_1498947850619379968" class="bloop_sign"><div style="font-family: helvetica, arial; font-size: 13px;" class="">-- <br class="">Adrian Zubarev<br class="">Sent with Airmail</div></div><br class=""><p class="airmail_on" style="margin: 15px 0px;">Am 2. Juli 2017 um 00:23:43, Jaden Geller (<a href="mailto:jaden.geller@gmail.com" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;" class="">jaden.geller@gmail.com</a>) schrieb:</p><blockquote type="cite" class="clean_bq" style="margin: 15px 0px;"><span style="margin-top: 0px; margin-bottom: 0px;" class=""><div class="" style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div class=""></div><div class="">I feel strongly that you shouldn’t be using autoclosure in these cases. Instead, write `true.whenTrue { … }` and `true.whenTrue(myClosure)`.<div class=""><br class=""><div class=""><blockquote type="cite" class="" style="margin: 15px 0px;"><div class="" style="margin-top: 0px;">On Jul 1, 2017, at 3:17 PM, Adrian Zubarev <<a href="mailto:adrian.zubarev@devandartist.com" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">adrian.zubarev@devandartist.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="" style="margin-bottom: 0px;"><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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><p class="" style="margin: 15px 0px; -webkit-margin-before: 0px;">I clearly disagree with your point. Autoclosure supposed to be a syntactically convenience feature to omit braces, which as a consequence needs to disable arguments. However it is not said that you cannot pass a closure with the same signature to the autoclosure, which currently is not possible unless it’s another autoclosure. This doesn’t feel right at all.</p><pre class="" 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;"><code class="" 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;">func foo(_: @autoclosure () -> Void) {}
func bar(_ test: @autoclosure () -> Void) {
foo(test) // works
}
let closure: () -> Void = {}
foo(closure) // error
</code></pre><p class="" style="margin: 15px 0px;">Here is another example where autoclosure takes over and produces false result even when the correct overload is present but the resolution ends up picking an autoclosure.</p><pre class="" 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;"><code class="" 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;">extension Bool {
/// #1
func whenTrue(execute closure: () -> Void) {
if self { closure() }
}
/// #2
func whenTrue(execute closure: @autoclosure () -> Void) {
if self { closure() }
}
/// #3
func whenTrue<T>(execute closure: @autoclosure () -> T) -> T? {
if self { return closure() }
return nil
}
}
let test: () -> Void = { }
// #3 wins and produces a wrong type () -> (() -> Void)?, but I expect #1 here
// () -> Void?
true.whenTrue(execute: test)
</code></pre><p class="" style="margin: 15px 0px;">A syntactical convenience feature should not disable explicitness!</p><div class="" style="margin: 15px 0px;"><br class="webkit-block-placeholder" style="-webkit-margin-before: 0px;"></div></div><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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><div id="bloop_customfont" class="" style="font-family: Helvetica, Arial; font-size: 13px; margin: 0px;"><br class=""></div><br class=""><div id="bloop_sign_1498946931420032000" class="bloop_sign"><div class="" style="font-family: helvetica, arial; font-size: 13px;">-- <br class="">Adrian Zubarev<br class="">Sent with Airmail</div></div><br class=""><p class="airmail_on" style="margin: 15px 0px;">Am 1. Juli 2017 um 19:46:55,<span class="Apple-converted-space"> </span><a href="mailto:jaden.geller@gmail.com" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">jaden.geller@gmail.com</a><span class="Apple-converted-space"> </span>(<a href="mailto:jaden.geller@gmail.com" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">jaden.geller@gmail.com</a>) schrieb:</p><blockquote type="cite" class="clean_bq" style="margin: 15px 0px;"><div dir="auto" class="" style="margin-top: 0px; margin-bottom: 0px;"><div class=""></div><div class=""><div class=""><span class="" style="margin-top: 0px; margin-bottom: 0px;"><br class=""></span></div><div class=""><span class="" style="margin-top: 0px; margin-bottom: 0px;"><br class="">On Jun 30, 2017, at 1:48 AM, Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">swift-evolution@swift.org</a>> wrote:<br class=""><br class=""></span></div><blockquote type="cite" class="" style="margin: 15px 0px;"><div class="" style="margin-top: 0px; margin-bottom: 0px;"><div class="bloop_markdown"><p class="" style="margin: 15px 0px; -webkit-margin-before: 0px;"><span class="" style="-webkit-margin-before: 0px; margin-top: 0px; margin-bottom: 0px;">Well as Jordan Rose said on the linked SR, option (1) will probably never happen. Option (3) only makes sense if all of the options are supported (in that case there wouldn’t be any need for explicit<span class="Apple-converted-space" style="-webkit-margin-before: 0px;"> </span><code class="" 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;">@autoclosure</code>, which could simply be merged into the closure type), or (2) is NOT supported so that one could pass a default autoclosure.</span></p><p class="" style="margin: 15px 0px;">It leaves us only with (2), which is potentially a (small) breaking change, but it also feels more like a fix. I cannot imagine anyone is wrapping whole closures with auto closure, nor do I think a ‘convenience’ operation should disable the explicit ability to pass in a closure with the same signature. The latter feels like a bug. Furthermore I think most code that relies on this is already doing something like.</p><pre class="" 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;"><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;">func bar(_ closure: @autoclosure () -> Int) { foo(closure)}
func foo(_ closure: () -> Int)
</code></pre><p class="" style="margin: 15px 0px;">But this is only an assumption of mine.</p><p class="" style="margin: 15px 0px;">Theoretically it suppose to work the other way around, right? Again<span class="Apple-converted-space" style="-webkit-margin-before: 0px;"> </span><code class="" 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;">@autoclosure</code><span class="Apple-converted-space"> </span>supposed to be a syntactical convenience feature which implies that it won’t disable *too* much from the closure type. Disallowing arguments is logical consequence but not the other issues I mentioned here and in the SR.</p><p class="" style="margin: 15px 0px;">—</p><p class="" style="margin: 15px 0px;">One question: Do we need to go through a full evolution process for pitch (2) or is a bug report enough here?</p></div></div></blockquote><div class="">Surely the former—I'm fully against this change, and imagine others are also. Autoclosure exists to provide opt-in lazy evaluation of values by wrapping them in a closure. I think it's semantically incorrect to accept an already wrapped value here, and adding this sort of implicit conversion can introduce potential ambiguity when used with generic functions.</div><div class=""><br class=""></div><div class="">Very large -1.</div><blockquote type="cite" class="" style="margin: 15px 0px;"><div class="" style="margin-top: 0px; margin-bottom: 0px;"><div class="bloop_markdown"></div><div class="bloop_original_html"><div id="bloop_customfont" class="" style="font-family: Helvetica, Arial; font-size: 13px; margin: 0px;"><br class=""></div><br class=""><div id="bloop_sign_1498806914384722944" class="bloop_sign"><div class="" style="font-family: helvetica, arial; font-size: 13px;">-- <br class="">Adrian Zubarev<br class="">Sent with Airmail</div></div><br class=""><p class="airmail_on" style="margin: 15px 0px;">Am 30. Juni 2017 um 00:59:45, Beta (<a href="mailto:rwidmann@apple.com" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">rwidmann@apple.com</a>) schrieb:</p><blockquote type="cite" class="clean_bq" style="margin: 15px 0px;"><div class="" style="margin-top: 0px; margin-bottom: 0px; word-wrap: break-word; -webkit-nbsp-mode: space;"><div class=""><div class=""><span class="">These are all interesting ideas at first blush, but introduce some oddities into the type system</span></div><div class=""><span class=""><br class=""></span></div><span class="">1. We accept this 😳. If we were to take this as an official language change it would mean that we would allow coercing T to (_) -> T by emitting a closure that takes an argument list (of arity given by the contextual type) that we throw away anyways. I would<span class="Apple-converted-space"> </span><i class="">much</i><span class="Apple-converted-space"> </span>prefer we diagnose this instead. @autoclosure is a syntactically convenient way to ask for laziness - that’s it.</span><div class=""><span class=""><br class=""></span><div class=""><span class="">2. Doing this collapses overloads on @autoclosure</span></div><div class=""><span class=""><br class=""></span></div><div class=""><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class=""><span class="" style="color: rgb(186, 45, 162);">func</span><span class="Apple-converted-space"> </span>foo(<span class="" style="color: rgb(186, 45, 162);">_</span><span class="Apple-converted-space"> </span>f :<span class="Apple-converted-space"> </span><span class="" style="color: rgb(186, 45, 162);">@autoclosure</span><span class="Apple-converted-space"> </span>() -><span class="Apple-converted-space"> </span><span class="" style="color: rgb(112, 61, 170);">String</span>) {}</span></div><div class="" style="margin: 0px; font-stretch: normal; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);"><span class="" style="color: rgb(186, 45, 162);">func</span><span class="Apple-converted-space"> </span>foo(<span class="" style="color: rgb(186, 45, 162);">_</span><span class="Apple-converted-space"> </span>f : () -><span class="Apple-converted-space"> </span><span class="" style="color: rgb(112, 61, 170);">String</span>) {}</div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Which is fine by me except for the code you would break that relies on this. I don’t see a reasonable migration path here - perhaps you have one in mind.</div><div class=""><br class=""></div><div class="">3. @autoclosure is a parameter attribute. Allowing it to appear in other positions is redundant and doesn’t actually accomplish anything outside of maintaining consistency with the first point.</div><div class=""><br class=""></div><div class="">I hope I don’t come off as too harsh. It’s just a little shocking to me that we accept the code in the linked SR.</div><div class=""><br class=""></div><div class="">~Robert Widmann</div><div class=""><br class=""><blockquote type="cite" class="" style="margin: 15px 0px;"><div class="" style="margin-top: 0px;">On Jun 24, 2017, at 9:10 AM, Adrian Zubarev via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">swift-evolution@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class="" style="margin-bottom: 0px;"><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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><p class="" style="margin: 15px 0px; -webkit-margin-before: 0px;">Hello folks,</p><p class="" style="margin: 15px 0px;">Here is a quick and straightforward pitch about<span class="Apple-converted-space" style="-webkit-margin-before: 0px;"> </span><code class="" 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;">@autoclosure</code>. Currently the attribute indicates that the caller has to pass an expression so that the braces can be omitted. This is a convenient behavior only, but it also has it’s shortcomings.</p><p class="" style="margin: 15px 0px;">I would like to propose an extension of that behavior.</p><div class="bloop_markdown"><br class="" style="-webkit-margin-before: 0px;"></div>1. Allow access to arguments and shorthand argument names:<br class=""><ol class="" style="margin: 15px 0px;"></ol><pre class="" 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;"><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;">// Bug: <a href="https://bugs.swift.org/browse/SR-5296" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none; -webkit-margin-before: 0px;">https://bugs.swift.org/browse/SR-5296</a>
func foo(_ test: @autoclosure (Int) -> Int = { $0 }) {
print(test(42))
}
// Convenient access using shorthand arguments
foo(Int(Double($0) * 3.14)))
</code></pre><div class="bloop_markdown"><br class="" style="-webkit-margin-before: 0px;"></div>2. Make<span class="Apple-converted-space"> </span><code class="" 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;">@autoclosure</code><span class="Apple-converted-space"> </span>only wrap when necessary:<br class=""><ol class="" style="margin: 15px 0px;"></ol><pre class="" 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;"><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;">func bar(_ test: @autoclosure () -> Int) {
print(test())
}
let test = { 42 }
// function produces expected type 'Int'; did you mean to call it with '()'?
bar(test)
</code></pre><div class="bloop_markdown"><br class="" style="-webkit-margin-before: 0px;"></div>3. Extend<span class="Apple-converted-space"> </span><code class="" 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;">@autoclosure</code><span class="Apple-converted-space"> </span>to closure types in general (this change is for consistent alignment):</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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><ol class="" style="margin: 15px 0px; -webkit-margin-before: 0px;"></ol><pre class="" 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;"><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;">// Note how we're using the shorthand argument list for this expression
let uppercaseWrapper: @autoclosure (String) -> String = $0.uppercased()
</code></pre><div class="" style="margin: 15px 0px;"><br class="webkit-block-placeholder" style="-webkit-margin-before: 0px;"></div></div><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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><div id="bloop_customfont" class="" style="font-family: Helvetica, Arial; font-size: 13px; margin: 0px;"><br class=""></div><br class=""><div id="bloop_sign_1498319089122447872" class="bloop_sign"><div class="" style="font-family: helvetica, arial; font-size: 13px;">-- <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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><div class="" style="-webkit-margin-before: 0px; margin: 15px 0px;"><br class="webkit-block-placeholder" style="-webkit-margin-before: 0px;"></div></div><span class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254); float: none; display: inline !important;">_______________________________________________</span><br class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><span class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254); float: none; display: inline !important;">swift-evolution mailing list</span><br class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><a href="mailto:swift-evolution@swift.org" class="" style="color: rgb(65, 131, 196); background-color: rgb(254, 254, 254); text-decoration: none; font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">swift-evolution@swift.org</a><br class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="" style="color: rgb(65, 131, 196); background-color: rgb(254, 254, 254); text-decoration: none; font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class="" style="font-family: Helvetica, Arial; font-size: 13px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"></div></blockquote></div><br class=""></div></div></div></div></blockquote></div><div class="bloop_markdown"></div></div></blockquote><blockquote type="cite" class="" style="margin: 15px 0px;"><div class="" style="margin-top: 0px; margin-bottom: 0px;"><span class="">_______________________________________________</span><br class=""><span class="">swift-evolution mailing list</span><br class=""><span class=""><a href="mailto:swift-evolution@swift.org" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">swift-evolution@swift.org</a></span><br class=""><span class=""><a href="https://lists.swift.org/mailman/listinfo/swift-evolution" class="" style="color: rgb(65, 131, 196); background-color: inherit; text-decoration: none;">https://lists.swift.org/mailman/listinfo/swift-evolution</a></span><br class=""></div></blockquote></div></div></blockquote></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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"></div></div></blockquote></div><br class=""></div></div></div></span></blockquote></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; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(254, 254, 254);"><br class="Apple-interchange-newline"></div></div></blockquote></div><br class=""></div></body></html>