Design and Architecture

<br />
Model model = new Model();<br />
model.Timestamp = "0227011";<br />
DateTime timestamp = model.Timestamp; // model implementation converts it and DateTime is a model data type<br />
<br />
ViewModel viewModel = ViewModel(model);<br />
DateTime timestamp = viewModel.Timestamp; // presentation implementation converts it and DateTime is a presentation type<br />

Nilzor wrote:

You have class A and class B which have some overlapping properties.

Nilzor wrote:

Maybe there isn't a definite answer?

I are Troll

either that or I've misunderstood completely and have resorted to flinging answers at a non-existent hypothetical question, sadly that wouldn't be the least productive thing I've done today....

class DbFactory {
    public static InterfaceDb Make(string kind) {
        switch (kind) {
            case "xml": return MakeXmlDb();
            case "sql": return MakeSqlDb();
        }
        throw new ArgumentException("kind");
    }
    private static InterfaceDb MakeXmlDb() {
        return new XmlDb();
    }
    private static InterfaceDb MakeSqlDb() {
        return new SqlDb();
    }
}

class DbFactory {
    public static InterfaceDb Make(string kind) {
        switch (kind) {
            case "xml": return new XmlDb();
            case "sql": return new SqlDb();
        }
        throw new ArgumentException("kind");
    }
}