0001-single-source-of-truth-008.swift

// We will create an enum as a namespace
enum Dependencies {
    // The same pattern that NotificationCenter's Name struct
    // follows.
    struct Name: Equatable {
        let rawValue: String
        static let `default` = Name(rawValue: "__default__")
        static func == (lhs: Name, rhs: Name) -> Bool { lhs.rawValue == rhs.rawValue }   
    }

    // The actual DI Container
    final class Container {
        // An array with the dependencies and the keys for them.
        private var dependencies: [(key: Dependencies.Name, value: Any)] = []
        
        // To use like a singleton.
        static let `default` = Container()
    }
}