C#: No implict conversion from Class to Class<Base>

Question

Following snippet wouldn\'t compile. With following error:

Cannot implicitly convert type \'Container\' to \'Container

Answer 1

(made wiki, in case of dups)

C# (3.0) doesn't support covariance of lists etc. C# 4.0 will support limited [co|contra]variance, but still not lists.

The problem is that with:

Container obj = new Container(); 

I could do:

obj.Add(new SomeOtherSubclass()); // SomeOtherSubclass : BaseClass

which would compile, but not work.

This behaviour is supported for arrays, but largely for historic reasons.