I would say this problem is about proper declaration of extension.
I would like to extend Array filled with generic Elements, where Element conforms to Equatable. I've managed to do that by :
extension Array where Element: Equatable{
// my code
}
However I'd like to know how to properly declare extension when the Array filled with Equatable elements is inside an Optional? I know that in this case I am actually extending protocol Optional, but I can't figure out the rest
I was thinking something like:
extension Optional where Wrapped: Array & Equatable {
// my code
}
Can't figure it out. Any ideas ?
I don't think you can't specify this constraint at the extension level, however you should be able to specify it at the function level:
extension Optional {
func myFunc<T: Equatable>() where Wrapped == [T] {
// do your thing
}
}
Cristik provided a good solution. An alternative is to write an extension to an optional collection of equatable elements:
extension Optional where Wrapped: Collection, Wrapped.Element: Equatable {
func foo() { }
}
This would be applicable to arrays, array slices, and other collections.
Depending on what the extension does, you may want to use a combination of Collection, MutableCollection, BidirectionalCollection, RandomAccessCollection.