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Once you recompile, you find a warning in the Visual Studio 2008 error window (see 

Figure 6-12).

Figure 6-12.

Oops! We just shadowed a member in our parent class.

To address this issue, you have two options. You could simply update the parent’s version of

Draw() using the override keyword (as suggested by the compiler). With this approach, the

ThreeDCircle type is able to extend the parent’s default behavior as required. However, if you don’t

have access to the code defining the base class (again, as would be the case in many third-party

libraries), you would be unable to modify the Draw() method as a virtual member, as you don’t have

access to the code file!

As an alternative, you can include the new keyword to the offending Draw() member of the

derived type (ThreeDCircle in this example). Doing so explicitly states that the derived type’s imple-

mentation is intentionally designed to hide the parent’s version (again, in the real world, this can be

helpful if external .NET software somehow conflicts with your current software).