Can a Swift Property Wrapper reference the owner of the property its wrapping?

Question

From within a property wrapper in Swift, can you someone refer back to the instance of the class or struck that owns the property being wrapped? Using self doesn\'t

Answer 1

The answer is no, it's not possible with the current specification.

I wanted to do something similar. The best I could come up with was to use reflection in a function at the end of init(...). At least this way you can annotate your types and only add a single function call in init().

fileprivate protocol BindableObjectPropertySettable {
    var didSet: () -> Void { get set }
}

@propertyDelegate
class BindableObjectProperty: BindableObjectPropertySettable {
    var value: T {
        didSet {
            self.didSet()
        }
    }
    var didSet: () -> Void = { }
    init(initialValue: T) {
        self.value = initialValue
    }
}

extension BindableObject {
    // Call this at the end of init() after calling super
    func bindProperties(_ didSet: @escaping () -> Void) {
        let mirror = Mirror(reflecting: self)
        for child in mirror.children {
            if var child = child.value as? BindableObjectPropertySettable {
                child.didSet = didSet
            }
        }
    }
}