Hands-On Design Patterns with Swift

Generic enums

In the following example, we will build a fully generic light:

enum State<T>: Equatable where T: Equatable {    case on    case off    case dimmed(T)}struct Bits8Dimming: Equatable {    let value: Int    init(_ value: Int) {        assert(value > 0 && value < 256)        self.value = value    }}struct ZeroOneDimming: Equatable {    let value: Double    init(_ value: Double) {        assert(value > 0 && value < 1)        self.value = value    }}let nostalgiaState: State<Bits8Dimming> = .dimmed(.init(10))let otherState: State<ZeroOneDimming> = .dimmed(.init(0.4))

The dim type is now specified as a part of the State type. This gives us a lot of flexibility, as well as validation. Wrapping the value into a small struct adds very little overhead in terms of performance, and allows us ...