I often find myself in a situation where I create a generic interface or class and then want to use different versions of this class or interface in a non generic way. For example I may have an interface like this:

interface ICanCreate<T>
{
    T NewObject();
}

Which allows a class to be a factory for that type. I then want to register these with a general factory class, so I try to write something like this:

public class Factory
{
    private Dictionary<Type, ICanCreate> mappings; // what do I put here????

    public void RegisterCreator<T>(ICanCreate<T> creator)
    {            
    }

    public T Create<T>()
    {            
    }
}

In the dictionary which type do I use for my value? I don't know if I am missing some sort of design principle and I am aware that this has a lot to do with co(ntra?)variance. Any help or ideas would be much appreciated.

c# generics covariance
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