Casting a generic collection to base type

Question

I\'ve got an IList that I want to cast to ICollection but when I attempt an explicit cast, I get null

Answer 1

This is called co-variance and while not currently supported with generics in .net, it will be added in the 4.0 framework (along with the opposite which is contra-variance).

This excellent video from PDC 2008 is session on C# futures given by Anders Hejlsberg:

http://channel9.msdn.com/pdc2008/TL16/