Rules for references when inheriting from base class

Question

Given that Project A is a C# Class Library and that Project B is a console application that has a dependency on Project A.

In Project A the following class is defined:

public class ActionMailNotifier : RazorMailerBase
{
        private readonly string _viewPath;
        private readonly EmailHost _emailConfig;
                   ...
                   ...
}

"RazorMailBase" is contained in an external dll, ActionMailer.dll, that is referenced by Project A.

In Project B the following class is defined:

public class EmailFareMonitorAlertNotifier : ActionMailNotifier
{
                        ...
                        ...
}

If ActionMailer.dll is not referenced in Project B the compiler generates an error message indicating that a reference to ActionMailer.dll is required. Is there a way to structure this such that a reference to the external dll is not required in Project B?

Answer 1

No. As long as EmailFareMonitorAlertNotifier ultimately derives from assembly external.dll you need to reference it so that the compiler and runtime have the information necessary to use the type.