Design and Architecture

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");
    }
}

Kevin Marois wrote:

1) Anyone see any issues with this? I welcome better ideas

Kevin Marois wrote:

2) How would the app know what snap-ins are available?

Kevin Marois wrote:

3) How do I keep someone from using the DLL in another .Net app?

Luc Pattyn wrote:

From your snippet it isn't really clear why you need two classes in the first place. I also expect real names for the classes would make things more obvious.

class Model
{
public:
    // Stuff...
};

class Controller
{
public:
    Controller(Model *model)
    {
        this->model = model
    }
};

class Controller
{
public:
    Controller()
    {
        this->model = new Model();
    }
};