Swift PropertyStore class for protocols

PropertyStore.swift

class PropertyStore<Root> {
    private var store = [AnyHashable : Any]()

    /// Runs the computedValue closure once and stores its result in a cache for the duration
    /// of the property store object's lifetime. Subsequent calls to this method will return the cached value.
    func cached<T>(_ keyPath: KeyPath<Root, T>, _ computedValue: @escaping () -> T) -> T {
        if let storedValue = store[keyPath] as? T {
            return storedValue
        }
        let value = computedValue()
        store[keyPath] = value
        return value
    }

    func clear<T>(property keyPath: KeyPath<Root, T>) {
        store[keyPath] = nil
    }

    func clearAll() {
        store.removeAll()
    }
}

// Example usage

protocol HasPropertyStore {
    var ps: PropertyStore<Self> { get }
}

protocol HasLocationCoordinate: HasPropertyStore {
    var latitude: Double { get }
    var longitude: Double { get }
    var locationCoordiante: CLLocationCoordinate2D { get }
}

extension HasLocationCoordinate {
    var locationCoordiante: CLLocationCoordinate2D {
        ps.cached(\.locationCoordiante) {
            .init(latitude: self.latitude, longitude: self.longitude)
        }
    }
}

struct PointOfInterest: Codable, HasLocationCoordinate {
    let name: String
    let latitude: Double
    let longitude: Double

    let ps = PropertyStore<PointOfInterest>()

    enum CodingKeys: String, CodingKey {
        case name
        case latitude
        case longitude
    }
}

let poi = PointOfInterest(name: "Nationaltheatret", latitude: 59.914472, longitude: 10.734372)
print(poi.locationCoordiante)
print(poi.locationCoordiante)

Property memoization discussion: https://forums.swift.org/t/memoization-of-swift-properties/38783