Question

I have the following interface which I’m trying to make COM-visible. When I try to generate the type-library it doesn’t like the fact that my implementation class derives from a generic-class.

Is it possible to use a generic class as a COM implementation class? (I know I could write a non-generic wrapper and export that to COM, but this adds another layer that I’d rather do without.)

[ComVisible(true)] public interface IMyClass {    ... }  [ComVisible(true), ComDefaultInterface(typeof(IMyClass))] [ClassInterface(ClassInterfaceType.None)] public class MyClass : BaseClass<IMyClass>, IMyClass {    ... }  

Error message:

Warning: Type library exporter encountered a type that derives  from a generic class and is not marked as  [ClassInterface(ClassInterfaceType.None)]. Class interfaces cannot be exposed for such types. Consider marking the type with  [ClassInterface(ClassInterfaceType.None)]  and exposing an explicit interface as the default interface to  COM using the ComDefaultInterface attribute.

Answer 1

Generic types and types that derive from a generic type cannot be exported. Set ComVisible(false) on your MyClass type. You’ll need to either create a non-generic class implementation or use the interface only.