CCW's and Duplicate Names

I had a short project during the Christmas/New Year's break.  I had to create some CCW's (COM Callable Wrappers) for a client that wanted to replace some existing COM objects with new .NET objects.  The requirement was that the existing COM clients (built with early-binding) would not need recompiling.  They have a product that allows their customers to write their own extensions.  So requiring hundreds of clients to recompile all of their extensions was something they wanted to avoid.

I started with the usual COM-interop procedures -- define an interface, use attributes for your GUIDs and DISPids, events, etc...  But then I ran into a problem.  One of their COM objects that I was replacing had both a method and an event with the same name.  Since they were a VB.NET shop I was doing all of this work in VB.NET.  Regardless of the language, .NET doesn't let you create a method and an event with the same name.

I had an idea.  While C# gives you two ways to implement an interface -- either explicit or implicit -- VB.NET only gives you one (which matches C#'s implicit implementation).  I wrote a quick test using explicit implementation of an interface method along with an event with the same name as the method.  C# was fine with that and as far as interop goes, the CCW didn't care.  It could find both the method and the event without any problems.

So I checked with the client and they were okay with using C# for the CCW's.  I moved my current code to C# and completed the wrappers.  So if you ever need to do some COM interop and run into an event and method with the same name, look into a C# wrapper with explicit interface implementation.