AssociatedHype.swift

public protocol DBWorker2 {
    associatedtype S: SequenceType

    func fetchObjectsFromStorage(type: S.Generator.Element.Type) -> Observable<S.Generator.Element>
    func saveObjectsToStorage(objects: S) -> Observable<Void>
}

public class DBWorker2Impl: DBWorker2 {
    public func fetchObjectsFromStorage(type: Item.Type) -> Observable<Item> {
        return Observable()
    }

    public func saveObjectsToStorage(objects: [Item]) -> Observable<Void> {
        return Observable()
    }
}