Fighting to get a COM visible VSTO Addin so its method can be used by VBA

So I am having some troubles and am learning too much about old technology. In short – my interface is COM visible to my VBA in my Excel code, but not the class. Crap – add the word public in front of class – fixed it. None-the-less here is a blog of what helped me solve my issue. I WANT (insist) early binding (aka intellisense 🙂 ) (Something close to my issue). Want to know even more … look at the links at the bottom of this article.

First – set up things properly.

  • Have a GUID for the interface IMyInterface and on the class MyClassO
  • Have the dual interface turned on on the interface and class

  • have a class MyClassO that inherits these Interface StandardOleMarshalObject, IMyInterface
  • in the ThisAddin.cs … have the following method
    • private MyClassO utilities;
      /// <summary>;
      ///
      /// </summary>
      /// <returns></returns>
      protected override object RequestComAddInAutomationService()
      {
      if (utilities == null)
      {
      utilities = new MyClassO();
      }return utilities;
      }
      
  • Did you check the Object Broswer in VBA???
    • Go to VBA Editor and press F2 or choose View-Object Browser
    • Change the “All Libraries” pull down to the name of you namespace or library
    • I saw my library – but just the interface.
  • Does the OLE / Com Object viewer show the same? It should
  • It did! so look at this article How COM works – this guy is WAY TO FAMILIAR – but is the reason I solved my issue – thanks man!

More articles that I wished I put here in my blog but was in my c# code so I copied it here – hope this helps

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