[swift-evolution] Properties with parameters

[Tim Vermeulen]

> Tim Vermeulen via swift-evolution<swift-evolution at ...>writes:
> 
> > Properties are great. They allow us to write the more naturally looking
> > 
> > myButton.hidden = true
> > 
> > instead of
> > 
> > myButton.setHidden(true)
> > 
> > However, they don't take any parameters. That’s why we still have to write
> > 
> > myButton.setImage(myImage, forState: .Normal)
> > 
> > instead of
> > 
> > myButton.imageForState(.Normal) = myImage
> > 
> > The syntax to write such a function would be pretty straight-forward:
> > 
> > var imageForState(state: UIControlState): UIImage? {
> > get { … }
> > set { … }
> > }
> Alternatively, in a Swift 2.2 overlay:
> 
> public extension UIButton {
> @nonobjc public subscript(imageForState state: UIControlState) ->UIImage? {
> get {
> return imageForState(state)
> }
> set {
> setImage(newValue, forState: state)
> }
> }
> }
> 
> myButton[imageForState: .Normal] = myImage
> 
> Apparently, C#'s "indexed properties" were rejected by the Swift design team:
> 
> <https://github.com/apple/swift/blob/master/docs/proposals/Accessors.rst>
> 
> -- Ben
> 
> 
> 

You can indeed do all those things with subscripts, but I think the function syntax would be more readable, especially in case of more than one parameter.