TIL @ attributes in Swift

Read chapter Attributes of Swift Reference. Good reference. Among others has useful example of using @dynamicMemberLookup for implementing PassthroughWrapper:

struct Point { var x, y: Int }

@dynamicMemberLookup
struct PassthroughWrapper<Value> {
    var value: Value
    subscript<T>(dynamicMember member: KeyPath<Value, T>) -> T {
        get { return value[keyPath: member] }
    }
}

let point = Point(x: 381, y: 431)
let wrapper = PassthroughWrapper(value: point)
print(wrapper.x)