<div dir="ltr">To have ? in the symbol is much better than looking back again and again to ensure variable is initialized or not for me.<div><br></div><div>Ruby style of fields naming is even better for reading, though a little burden for writing.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Jan 9, 2016 at 3:38 PM, Brent Royal-Gordon via swift-evolution <span dir="ltr"><<a href="mailto:swift-evolution@swift.org" target="_blank">swift-evolution@swift.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">> var x:Int = none // uninitialized but not an optional<br>
><br>
> print(x) // run-time error as x is uninitialized<br>
><br>
> if x == nil { … } // compile time error… x can never be nil because it is not an optional<br>
><br>
> if x == none { x = 2 } // … but it can be uninitialized<br>
><br>
> Optionals can also be uninitialized:<br>
><br>
> var y:Int? = none // uninitialized and an optional<br>
><br>
> if y == nil { … } // run-time error as y is uninitialized<br>
><br>
> y = nil<br>
><br>
> if y == nil { … } // fine<br>
<br>
</span>I think there *may* be a case for this as a strictly static check. That is, setting a variable to `none` would be a way to explicitly mark the current state as invalid, and ask the compiler to prove that it's not used again until you've reinitialized it. But your example of `x == none` would not make any sense—`none` would not be a thing that existed at runtime. That's a very niche feature, though, and I'd need convincing that it's helpful.<br>
<br>
I'm strongly opposed to this feature as a runtime construct. It's basically just reintroducing null references, which is an anti-goal.<br>
<span class="HOEnZb"><font color="#888888"><br>
--<br>
Brent Royal-Gordon<br>
Architechies<br>
</font></span><div class="HOEnZb"><div class="h5"><br>
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</div></div></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr">Best Regards!<br><br>Yang Wu<br>--------------------------------------------------------<br>Location: Pudong, Shanghai, China.<br>EMail : <a href="mailto:pinxue@gmail.com" target="_blank">pinxue@gmail.com</a><br>Website: <a href="http://www.time2change.mobi" target="_blank">http://www.time2change.mobi</a> <a href="http://rockplayer.com" target="_blank">http://rockplayer.com</a><br>Twitter/Weibo : @pinxue<br><a href="http://www.pinxue.net" target="_blank"></a></div></div>
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