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Conditional conformances
Basics article available: ProtocolsSwift 4.1 is here! One of the key features it brings is conditional conformances, which lets you have a type only conform to a protocol under certain constraints.
protocol UnboxTransformable {
associatedtype RawValue
static func transform(_ value: RawValue) throws -> Self?
}
extension Array: UnboxTransformable where Element: UnboxTransformable {
typealias RawValue = [Element.RawValue]
static func transform(_ value: RawValue) throws -> [Element]? {
return try value.compactMap(Element.transform)
}
}
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