<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="">I’ll take the opposite stance. Why limit this to initialization? I’d love to be able to guard assignments to *any* variable, whether it’s a property or not:</div><div class=""><br class=""></div><div class="">func foo() {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>let bar: String</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>if someCondition {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>guard bar = mightReturnOptional() else {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>return</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>} else {</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>bar = wontReturnOptional()</div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>}</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>self.doSomethingWith(bar)</div><div class="">}</div><div class=""><br class=""></div><div class="">As opposed to:</div><div class=""><br class=""></div><div class=""><div class="">func foo() {</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>let bar: String</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>if someCondition {</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>guard let _bar = mightReturnOptional() else {</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>return</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>}</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>bar = _bar</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>} else {</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>bar = wontReturnOptional()</div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>}</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space: pre;"> </span>self.doSomethingWith(bar)</div><div class="">}</div></div><div class=""><br class=""></div><div class="">Charles</div><br class=""><div><blockquote type="cite" class=""><div class="">On Jul 25, 2017, at 4:13 PM, Niels Andriesse 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="">Although I have come across this problem as well (particularly when initializing from JSON), I don't think the solution is to fundamentally change initialization behavior like this, because 1. ) that is probably going to break a good deal of existing code and 2. ) I think that the introduction of the Codable protocol in Swift 4 will eliminate most cases where this is really a problem.<br class=""><div class="gmail_quote"><div dir="ltr" class="">On Wed, 26 Jul 2017 at 02:30 Taylor Swift via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="">swift-evolution@swift.org</a>> wrote:<br class=""></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr" class="">I’d be in favor of this.<br class=""></div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Tue, Jul 25, 2017 at 5:44 AM, philohan95 via swift-evolution <span dir="ltr" class=""><<a href="mailto:swift-evolution@swift.org" target="_blank" class="">swift-evolution@swift.org</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I think the current way to initiate models in a Failable Initializer `init?()` is overly verbose and should be shortened down so less boilerplate should be needed.<br class="">
<br class="">
The current way:<br class="">
<br class="">
```<br class="">
let someProperty: Any<br class="">
let anotherProperty: Any<br class="">
<br class="">
init?(data: [String: Any]) {<br class="">
guard<br class="">
let someProperty = data["some_key"],<br class="">
let anotherProperty = data["another_key"]<br class="">
else {<br class="">
return nil<br class="">
}<br class="">
<br class="">
self. someProperty = someProperty<br class="">
self. anotherProperty = anotherProperty<br class="">
}<br class="">
```<br class="">
<br class="">
As you can see we had to use the properties twice (this would also be the case of `if let`) making the initializer twice as long as necessary and becomes a pain to implement when having more than 1 property.<br class="">
<br class="">
My idea is extending the power of the `guard` statement<br class="">
<br class="">
Idea:<br class="">
init?(data: [String: Any]) {<br class="">
guard<br class="">
someProperty = data["some_key"], // Currently fails because `self` us used before all stored properties are initialized<br class="">
anotherProperty = data["another_key"]<br class="">
else {<br class="">
return nil<br class="">
}<br class="">
}<br class="">
}<br class="">
<br class="">
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</blockquote></div><br class=""></div>
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