COM Interop in .Net I had to make COM Interop with .Net and VB6 work a few months back. Since I'll probably have to do that again soon, I figured a post on this was timely.

Getting everything to work correctly wasn't as easy as advertised. True, I did some Google searches for useful information. I did get the whole thing to work, complete with IntelliSense working from VB6. It was great.

A couple of months after that, I stumbled across this article that talks about all the stuff they don't tell you (that I had to figure out). I took a quick read of it and I think it covered all the stuff I had to figure out. I was going to write down the real steps, but why bother, I think they're all here!

Besides that article, there are a couple of other related articles I ran into that were useful. I might as well list those, too:

• Advanced COM Interop from MS .Net Framework Developer's Guide
• Codes in FACILITY_ITF. This is useful if you're setting up customer HRESULTs to be returned from your .Net exceptions. Also, the Structure of COM Error Codes is a handy reference.
• MS Article: Registration-Free COM Interop
• Managed and Unmanaged Code Interoperability Notes
• Understanding Classic COM Interoperability with .NET Applications

9/8/2005: I stumbled across another useful attribute today: ComClassAttribute. The main article referenced above doesn't reference this attribute. It's in the Microsoft.VisualBasic namespace (why not just put it with everything else)?

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