>I thought I'd used this sort of construct before. But the compiler insists that the type of Parent in Test must be BaseClass.

public interface ITest
>    {
>        BaseClass Parent { get; }
>    }
>
>    public class BaseClass {}
>
>    public class DerivedClass : BaseClass{}
>
>    public class Test : ITest
>    {
>        public DerivedClass Parent
>        {
>            get {return new DerivedClass(); }
>        }
>    }

Am I cracking up?

Viv,

I agree with Bonnie

Your interface says the return type should be BaseClass and you're returning another type. iow the signature of the interface does not match

See last line of error message ( I have taken my namespace out to make it clearer)

Error	1	'Test' does not implement interface member 'ITest.Parent'.
 'Test.Parent' cannot implement 'ITest.Parent' because it does not have the matching return type of 'BaseClass'.