Really? My observation from a quick test is that "a? = b" assigns b to a if a already has a value, or does nothing if it's nil. This is sort of the opposite of what's being proposed, which is that "a ?= b" should assign to a only if it does NOT have a value.<br><div class="gmail_quote"><div dir="ltr">On Wed, Jan 25, 2017 at 9:33 AM Joe Groff via swift-evolution <<a href="mailto:swift-evolution@swift.org">swift-evolution@swift.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br class="gmail_msg">
> On Jan 25, 2017, at 8:40 AM, Nichi Shin via swift-evolution <<a href="mailto:swift-evolution@swift.org" class="gmail_msg" target="_blank">swift-evolution@swift.org</a>> wrote:<br class="gmail_msg">
><br class="gmail_msg">
> I’d like to propose a new operator for optional assignment in Swift.<br class="gmail_msg">
><br class="gmail_msg">
> The idea is that by using this operator (e.g. by doing a ?= b), the optional on the right would be assigned to the variable on the left only when it has something to assign (i.e. when it's not nil).<br class="gmail_msg">
<br class="gmail_msg">
`a? = b` already does this. Maybe we need a fixit to make that more apparent, though.<br class="gmail_msg">
<br class="gmail_msg">
-Joe<br class="gmail_msg">
<br class="gmail_msg">
><br class="gmail_msg">
> The implementation could be something as follows:<br class="gmail_msg">
><br class="gmail_msg">
> /// Optional Assignment Operator<br class="gmail_msg">
> infix operator ?=: AssignmentPrecedence<br class="gmail_msg">
><br class="gmail_msg">
> func ?=<T>(left: inout T, right: T?) {<br class="gmail_msg">
> if right != nil {<br class="gmail_msg">
> left = right!<br class="gmail_msg">
> }<br class="gmail_msg">
> }<br class="gmail_msg">
><br class="gmail_msg">
> func ?=<T>(left: inout T?, right: T?) {<br class="gmail_msg">
> if right != nil {<br class="gmail_msg">
> left = right<br class="gmail_msg">
> }<br class="gmail_msg">
> }<br class="gmail_msg">
><br class="gmail_msg">
> I hope you will consider adding this on a future release of this great programming language.<br class="gmail_msg">
><br class="gmail_msg">
> Kind regards,<br class="gmail_msg">
> N. S.<br class="gmail_msg">
> _______________________________________________<br class="gmail_msg">
> swift-evolution mailing list<br class="gmail_msg">
> <a href="mailto:swift-evolution@swift.org" class="gmail_msg" target="_blank">swift-evolution@swift.org</a><br class="gmail_msg">
> <a href="https://lists.swift.org/mailman/listinfo/swift-evolution" rel="noreferrer" class="gmail_msg" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class="gmail_msg">
<br class="gmail_msg">
_______________________________________________<br class="gmail_msg">
swift-evolution mailing list<br class="gmail_msg">
<a href="mailto:swift-evolution@swift.org" class="gmail_msg" target="_blank">swift-evolution@swift.org</a><br class="gmail_msg">
<a href="https://lists.swift.org/mailman/listinfo/swift-evolution" rel="noreferrer" class="gmail_msg" target="_blank">https://lists.swift.org/mailman/listinfo/swift-evolution</a><br class="gmail_msg">
</blockquote></div>