comvisible

I've made a simple C# DLL (that's part of a much larger project) using VS2005. I need to use the DLL in Excel via VBA code so I am using COM Interop on the assembly. I am trying to make the build process automatically generate the necessary TLB file so that I don't need to go to the command line and use regasm after every build. My problem is that although the DLL compiles and builds fine, it does not generate a TLB file. Instead, the error in the title prints out in the output box. I've gotten other DLLs to build TLB files by going to the project's properties in VS2005 -> Build -> Output ->

MSDN has this article about [ComVisible] attribute . I don't quite get what happens when one sets [ComVisible(true)] . MSDN says The default is true , which indicates that the managed type is visible to COM. This attribute is not needed to make public managed assemblies and types visible ; they are visible to COM by default. Only public types can be made visible. So they say public types are visible to COM by default. But they also say only public types can be made visible by setting [ComVisible(true)] . It does not makes sense: if public types are visible by default, then how does setting

When you create a new C# project in Visual Studio, the generated AssemblyInfo.cs file includes an attribute specifying an assembly GUID. The comment above the attribute states that it is used "if this project is exposed to COM". None of my assemblies contain types which need to be visible to COM, so I have marked my assembly with [assembly: ComVisible(false)] . So is there any point in specifying a GUID? My feeling is that the answer is "no" - so why does the default AssemblyInfo.cs file contain both [assembly: ComVisible(false)] and [assembly: Guid("...")] ? Edit: To summarize the responses:

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 { ... }