KeyPathEditable Protocol

KeyPathEditable.swift

enum KeyPathError: Error {
    case unableToCast(String)
}

protocol KeyPathEditable {
    func update<KeyPathType>(path: PartialKeyPath<Self>, to value: KeyPathType) throws -> Self
}

extension KeyPathEditable {
    func update<KeyPathType>(path: PartialKeyPath<Self>, to value: KeyPathType) throws -> Self {
        guard let writableKeyPath = path as? WritableKeyPath<Self, KeyPathType> else {
            throw KeyPathError.unableToCast("because of passed \(value) value data type")
        }
        var copy = self
        copy[keyPath: writableKeyPath] = value
        return copy
    }
}