[swift-evolution] Proposal: partial initialization before returning nil from an initializer

[Keith Smiley]

I believe this has already been fixed here:
https://github.com/apple/swift/commit/f524802e129f17de16fa6f8c3f08e5bcf75cc581
On Thu, Dec 17, 2015 at 10:01 Félix Cloutier <swift-evolution at swift.org>
wrote:

> Hi all,
>
> Initializers can now fail, but objects still need to be fully initialized
> before you can return `nil` from them. For instance:
>
>         class Foo {
>                 let bar: Int
>                 init?(baz: Int) {
>                         guard baz < 100 else {
>                                 return nil
>                         }
>                         self.bar = baz
>                 }
>         }
>
> This trivial example causes the following error: "all stored properties of
> a class instance must be initialized before returning nil from an
> initializer".
>
> For integers, that's easy: you can simply set them to zero. However,
> sometimes, you'd want initialization to fail because the arguments you
> received don't allow you to properly initialize a member. In these cases,
> you have to make the fields Optionals (implicitly unwrapped or not) to
> overcome this.
>
> I remember that Chris said that this is a temporary issue and that it
> would eventually be fixed. I'm starting this thread because I'd love to
> have this with or before Swift 3 and I'd like to see who thinks this is big
> enough of an issue to rival the proposals we already have.
>
> Félix
>
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>
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