VBA and C# interop

Question

Hi everyone I need to call a DLL in C# from a VBA application. The DLL will expose a method that returns a complex class. I tested the interop and it worked fine when the method returns a primitive type but when it returns a complex object it does not work. I precise I don't know anything at COM (I don't even understand how those GUIDs are generated!) I have Visual Studio .NET Express what's the easiest method you would recommend to me? Thanks in advance Mark

Vulpes · Answer

Unfortunately COM is anything but simple but I've found something here which might help : http://blogs.artinsoft.net/Mrojas/archive/2010/06/23/Exposing-C-Classes-thru-Interop.aspx

Vulpes · Answer

The only realistic way for C# to interoperate with VBA is using COM so I imagine you must have already created a COM-aware DLL and registered it with tlbexp.exe for anything to work at all. As far as exposing your own classes are concerned they must be public and to be on the safe side they should be decorated with the attribute [ComVisible(true)]. So I'd try that if you're not doing it already.

Mark Morrisson · Answer

Thank you very much! Mark

Mark Morrisson · Answer

In fact Visual Studio does all this stuff for you if you check the right options (registering the COM object and making them visible). As I said in my question the problem is not to build a DLL that exposes a method it's to build a DLL that exposes a method that returns a complex type. It does not work alone so I'm looking for a simple tutorial/explanation to learn how to do it the simple way.