Factory Pattern without a Switch or If/Then

Question

I\'m looking for a simple example of how to implement a factory class, but without the use of a Switch or an If-Then statement. All the examples I can find use one. F

Answer 1

public class PositionFactory
{
    private Dictionary _positions;

    public PositionFactory()
    {
        _positions = new Dictionary();
    }

    public void RegisterPosition(int id) where PositionType : Position
    {
        _positions.Add(id, typeof(PositionType));
    }

    public Position Get(int id)
    {
        return (Position) Activator.CreateInstance(_positions[id]);
    }
}

Used like this:

            var factory = new PositionFactory();
            factory.RegisterPosition(0);
            factory.RegisterPosition(1);

            Position p = factory.Get(0); //Returns a new Manager instance