If we go back to your original example:
func scaleAndCropImage(
image: UIImage,
toSize size: CGSize,
fitImage: Bool = true
) -> UIImage {
There is a different type of sugar that I would like to have: Having label
stand for `true` when we have a defaulted boolean flag, whose default value is
false.
At call site we either say:
scaleAndCropImage(image: myImage, toSize: mySize)
or:
scaleAndCropImage(image: myImage, toSize: mySize, fitImage)
We could still use:
scaleAndCropImage(image: myImage, toSize: mySize, fitImage: true)
or
scaleAndCropImage(image: myImage, toSize: mySize, fitImage: false)
Note that this is addressing a different situation: When we have multiple
boolean flag parameters that can be combined like an OptionSet.
This is purely sugar: if the identifier matches the label of a defaulted to
false boolean flag, it is interpreted as if the flag was passed as true. Other
than that there is no effect.
I also like your idea as long as we put a limitation like what you proposed:
Having it strictly be a UInt8 (or whatever) enum. Still the general resilience
issues with enums remain and may get more complicated with this addition.
> On May 31, 2016, at 3:00 PM, Erica Sadun via swift-evolution
> <[email protected]> wrote:
>
>
>> On May 31, 2016, at 3:20 PM, Brent Royal-Gordon <[email protected]>
>> wrote:
>>
>>> func scaleAndCropImage(
>>> image: UIImage,
>>> toSize size: CGSize,
>>> operation: (.Fit | .Fill) = .Fit
>>> ) -> UIImage {
>>
>> As I said the last time this proposal came up, I think this is great right
>> up until the moment you need `operation` to be computed or kept in a
>> variable. Then you need to start copying your anonymous enum type all over
>> your source, and there's no central place to make changes. The same thing is
>> true of tuples, but tuples are easy to structure and destructure from
>> individual values on the spot; anonymous enums aren't really like that.
>
> And the obvious answer is you can have up to 255 of these babies for the
> anonymous enum type, and be able to pass numerical equivalents UInt8 with
> compile time substitution. That the ad-hoc enumeration is basically a
> syntactic shorthand for UInt8, with an enforced upper bound compile time
> check simplifies everything including switch statements.
>
> -- E
>
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