[swift-evolution] Pitch: Remove default initialization of optional bindings

Matthew Johnson matthew at anandabits.com
Mon Nov 6 16:41:10 CST 2017


> On Nov 6, 2017, at 4:33 PM, Slava Pestov via swift-evolution <swift-evolution at swift.org> wrote:
> 
> Hi all,
> 
> Right now, the following two declarations are equivalent:
> 
> struct S {
>  var x: Int?
> }
> 
> struct S {
>  var x: Int? = nil
> }
> 
> That is, mutable bindings of sugared optional type (but not Optional<T>!) always have a default value of ‘nil’. This feature increases the surface area of the language for no good reason, and I would like to deprecate it in -swift-version 5 with a short proposal. Does anyone feel strongly about giving it up? I suspect most Swift users don’t even know it exists.

I don’t have too strong an opinion on this, leaning towards being supportive.  That said, I think you underestimate the source breakage it will cause.  I have seen a lot  of code this change will break (albeit in a trivial way that’s easy to migrate).

> 
> Slava
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