Non Generic Versions of Generic classes and interfaces
c#, covariance, generics
Solution
You either have to just use `object` in your dictionary declaration (it's all private, and you can verify that you'll never put the wrong kind of thing in there) or declare a non-generic `ICanCreate` interface which `ICanCreate<T>` extends.
Basically you want a type relationship which can't be expressed in C# - and whenever that happens, you end up with a slightly unpleasant solution, but it looks like you can isolate the ugliness here (i.e. keep it within the single class).
Problem
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.