How are optional values implemented in Swift?

Question

I wonder how the value types in Swift (Int, Float...) are implemented to support optional binding (\"?\"). I assume those value types are not allocated on the heap, but on t

Answer 1

Swift is open source since yesterday. You can see the implementation on GitHub: https://github.com/apple/swift/blob/master/stdlib/public/core/Optional.swift

public enum Optional : ExpressibleByNilLiteral {

    case none
    case some(Wrapped)

    public init(_ some: Wrapped) { self = .some(some) }

    public init(nilLiteral: ()) {
        self = .none
    }

    public var unsafelyUnwrapped: Wrapped {
        get {
            if let x = self {
                return x
            }
            _debugPreconditionFailure("unsafelyUnwrapped of nil optional")
        }
    }
}