Implement multiple times the same generic interface that includes properties with different type parameters

Question

Well from the beginning, I've got a simple generic interface:

public interface IItemContainer<T> where T : Item
{
    T ChosenItem { get; set; }
}

And an class that implements it multiple times:

public class ChosenItemsContainer : IItemContainer<FabulousItem>, IItemContainer<NiceItem>, IItemContainer<GreedyItem>
{

    public FabulousItem ChosenItem { get; set; }
    NiceItem IItemContainer<NiceItem>.ChosenItem { get; set; }
    GreedyItem IItemContainer<GreedyItem>.ChosenItem { get; set; }
}

I can't make the ChosenItems of types NiceItem and GreedyItem public, and also I can't access it like this:

ChosenItem<GreedyItem> = new GreedyItem();

cuz' I've got an error:

'GreedyItem' is a type, which is not valid in the current context

Is there anyway to use those props in this manner or I've got it all wrong and should do It with Dictionary or other way?

Answer 1

When you like to keep your generic IItemContainer you can implement a GetChosenItem and SetChosenItem method like this.

public class ChosenItemsContainer : IItemContainer<FabulousItem>, IItemContainer<NiceItem>, IItemContainer<GreedyItem>
{
    FabulousItem IItemContainer<FabulousItem>.ChosenItem { get; set; }
    NiceItem IItemContainer<NiceItem>.ChosenItem { get; set; }
    GreedyItem IItemContainer<GreedyItem>.ChosenItem { get; set; }

    public T GetChosenItem<T>()
        where T : Item
    {
        return ((IItemContainer<T>)this).ChosenItem;
    }

    public void SetChosenItem<T>(T value)
        where T : Item
    {
        ((IItemContainer<T>)this).ChosenItem = value;
    }
}

Which comes very close to what you were trying to do.

container.SetChosenItem<NiceItem>(new NiceItem());