Update
Clarification via EricGu…having an Everett assembly reference a Whidbey assembly is not a supported scenario, plus generic metadata will cause weird things to happen. _
_Thanks Eric :)
Someone sent a question recently to an internal alias so I thought I would share. The question was what will happen when a C# V1 component consumes a C# V2 component that exposes a generic class. First some background information, there are two types of compatibility, backward compatibility and forward compatibility.
Backward compatibility refers to a future version of a product, like Whidbey, supporting already existing functionality like something found in .
Forward compatibility refers to an older product, like Everett, being able to support a new feature like generics.
As you can imagine, it’s easier to add backward compatibility since it is a known thing. Designing for forward compatibility can be more difficult as it is an unknown thing. The goal of C# Whidbey is geared more towards backward compatibility so that if you write a component today for version 1.x, your component will “just work” in C# Whidbey.
I decided to test what forward compatibility will work with the current Tech preview for a VS Whidbey component to be used in VS 2003. To test forward compatibility, I created a simple generic class with two static methods. The first method returns a generic collection, the second returns a non-generic collection.
V2 Code
public class GenericClass
{
public static List
{
List
l.Add(1);
return l;
}
public static ArrayList ReturnNonGeneric()
{
ArrayList ar = new ArrayList();
ar.Add(1);
return ar;
}
}
I added a reference to the GenericClass in VS 2003. Using IntelliSense, the only method that is available to execute is GenericClass.ReturnNonGeneric() since VS 2003 doesn’t understand a non-generic type. Since VS 2003 doesn’t understand generic types it can’t call the ReturnGeneric() method.