[swift-evolution] Idea: Properties in Failable Initializers less verbose

[Taylor Swift]

I’d be in favor of this.

On Tue, Jul 25, 2017 at 5:44 AM, philohan95 via swift-evolution <
swift-evolution at swift.org> wrote:

> 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.
>
> The current way:
>
> ```
> let someProperty: Any
> let anotherProperty: Any
>
> init?(data: [String: Any]) {
>         guard
>                 let someProperty = data["some_key"],
>                 let anotherProperty = data["another_key"]
>         else {
>                 return nil
>         }
>
>         self. someProperty = someProperty
>         self. anotherProperty = anotherProperty
> }
> ```
>
> 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.
>
> My idea is extending the power of the `guard` statement
>
> Idea:
>         init?(data: [String: Any]) {
>                 guard
>                         someProperty = data["some_key"], // Currently
> fails because `self` us used before all stored properties are initialized
>                         anotherProperty = data["another_key"]
>                 else {
>                         return nil
>                 }
>         }
> }
>
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