[swift-evolution] [Proposal Draft] Flexible memberwise initialization

[Félix Cloutier]

I would like let rules to be consistent whether you have a memberwise init or not; and I would like them to be consistent with classes.

I think this places me on Guillaume's side here.

Félix

> Le 22 déc. 2015 à 14:20:47, Guillaume Lessard via swift-evolution <swift-evolution at swift.org> a écrit :
> 
> 
>> On 22 déc. 2015, at 12:02, Matthew Johnson <matthew at anandabits.com> wrote:
>> 
>> This is not an attempt to subvert `let` properties.  The `= 1` in the declaration can very reasonably be viewed as a default value that should be used if the member is not otherwise initialized.
> 
> I see it as a definition.
> 
> 
>> Why would you have an immutable instance member that is always going to have a constant value of 1?
> 
> I’m not convinced the language must prevent people from doing useless things.
> The current model is clear. The one you suggest is much murkier.
> (And this is a kind of situation where I would expect nifty optimizations.)
> 
> 
>> That just wastes space by duplicating the constant value in many instances.  However it is quite reasonable to have an immutable instance member that defaults to 1, but may have a different value depending on the initializer that is used for the instance.
> 
> Shouldn’t one write an initializer with a default value, then?
> 
> struct A {
> let property: Int
> init(property: Int = 1) { self.property = property }
> }
> 
> Much clearer. Using initialized `let` properties as a mere suggestion involves mental gymnastics.
> 
> Guillaume Lessard
> 
> _______________________________________________
> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution