Question

I was thinking of a generic method where T should be interface but it can be the descendant of IFace

public static T Get<T>(SomeClass foo) where T : IFace {
  if(smthing)
    return Activator.CreateInstance(type, true);
}

so i can call

Class.Get<IFace>(smth)
Class.Get<IFaceDescend>(smt)

but not

Class.Get<Class2>(smt)

Answer 1

No, you can’t do this. You can test for it at execution time:

if (!typeof(T).IsInterface)
{
    throw ...;
}

… but you can’t express it as a compile-time constraint on T.