[swift-evolution] Support for pure setters

[Jessy Catterwaul]

I do not agree about the implication. A property can be gotten, set, or both, in at least C#, where I used a ton of set-only properties.

Here is a large list of properties that are set-only:
https://developer.apple.com/library/ios/documentation/Metal/Reference/MTLRenderCommandEncoder_Ref/index.html#//apple_ref/swift/intf/c:objc(pl)MTLRenderCommandEncoder

Some of them require more than a single value, for setting. Tuple assignment or named subscripts are the best way I currently know to handle that. Having them be functions that begin with “set” and take arguments feels archaic and not specific enough, to me.

func setStencilFrontReferenceValue(frontReferenceValue: UInt32,
   backReferenceValue: UInt32
)
setStencilFrontReferenceValue(0, backReferenceValue: 1)

versus

var stencilReferenceValues: (front: UInt32, back: UInt32) {set}
stencilReferenceValues = (front: 0, back: 1)


func setVertexSamplerState(sampler: MTLSamplerState?, atIndex index: Int)
setVertexSamplerState(someState, atIndex 0)

versus

subscript vertexSamplerState(index: Int): MTLSamplerState? {set}
vertexSamplerState[0] = someState


The former options, I feel are not Swift, but C masquerading as Swift.


> Cc:swift-evolution at swift.org
> Subject:[swift-evolution] Support for pure setters
> Date:February 3, 2016 at 3:31:16 PM EST
> 
> 
> 
> > On Feb 3, 2016, at 12:21 PM, Jessy Catterwaul<mr.jessy at gmail.com>wrote:
> > 
> > Joe, to attempt to set foo.x doesn’t make sense. If foo cannot be gotten, a property of it will be inaccessible for getting or setting.
> > 
> > Set-only properties are always computed, and only used via assignment.
> > 
> > e.g. foo = value
> I understand that. If that's all you're allowed to do with a set-only property, then this is just sugar over 'setFoo(value)', and I think the sugar implies you could do more with 'foo' than you really can. I don't think it's worth the complexity.
> 
> -Joe
> 
> 
> 
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