[swift-evolution] Ad hoc enums / options

[Erica Sadun]

Here's a function signature from some code from today:

func scaleAndCropImage(
    image: UIImage,
    toSize size: CGSize,
    fitImage: Bool = true
    ) -> UIImage {


And here's what I want the function signature to actually look like:

func scaleAndCropImage(
    image: UIImage,
    toSize size: CGSize,
    operation: (.Fit | .Fill) = .Fit
    ) -> UIImage {


where I don't have to establish a separate enumeration to include ad-hoc enumeration-like semantics for the call. A while back, Yong hee Lee introduced anonymous enumerations (and the possibility of anonymous option flags) but the discussion rather died.

I'm bringing it up again to see whether there is any general interest in pursuing this further as I think the second example is more readable, appropriate, and Swifty than the first, provides better semantics, and is more self documenting.

Thanks for your feedback,

-- Erica

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