C# Covariance issue?
You can also use this to do casting with conversions if needed: public static IEnumerable CastAll(this IEnumerable items) { var p = Expression. Parameter(typeof(TItem), "i"); var c = Expression. Convert(p, typeof(TDest)); var ex = Expression.
Lambda(c, p).Compile(); foreach (var item in items) { yield return ex(item); } } From http://adventuresdotnet.blogspot.com/2010/06/better-more-type-safe-alternative-to.html.
Let's name your classes Animal for A, Barker for B, and Dog for D. Actually C is wider than Dog : C. Dog is parametrized with Barker.
Have you seen barking elephants? You need to declare some covariant interface to allow assignment of class instantiated with more derived type argument C to object instantiated with less derived type argument C. You can use empty interface, like @NickW suggested, but you will not be able to do something with instance of that interface (it's empty!).
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.
Related Questions
Interface covariance issue?
Covariance/Contravariance Conundrum when using generic interface constraints?
Covariance not working with generic dictionary entry?
LINQ to SQL Covariance - is this the right way to do this?
C# : Is Variance (Covariance / Contravariance) another word for Polymorphism?
Covariance in c?