Whats the name of the C# feature that allows you to implicitly consider a List<ChildClass> as a List<ParentClass>

Question

It is relevant to a technical discussion I'm participating in.

Answer 1

You're talking about generic covariance - but it doesn't apply to List<T>, which is invariant.

It does apply to IEnumerable<T> though:

IEnumerable<ChildClass> children = new List<ChildClass>();
IEnumerable<ParentClass> parents = children;

Answer 2

I think you mean Covariance and Contravariance.