Question

Background

This may be incredibly basic, or it may be completely impossible. Being new to COM, I don’t know, and given my limited COM vocabulary, Google has failed me.

I have an ATL/MFC C++ COM object with many data structures defined internally.
I also have a C# project that references this COM object. In C#, I can call the methods exposed via the C++ side .IDL file and get valid results (finally!).

Question

I would like to use the .IDL file to somehow expose the 100 or so C++ data structures to C# (preferably without wrapping each one individually). Then in C#, I would simply populate the appropriate structure and call a COM method passing the data structure into C++.

Basically, I want to reuse the already defined C++ structures in C#. Is this possible? If so, how?

If it matters, I’m using Visual Studio 2010 and .NET 4 Framework.

Thanks a bunch.

Answer 1

So it turns out I was trying to put the structure in the wrong place in the IDL file. I was trying to add it to the library definition, and for whatever reason, that did not work.

Placing it in the interface definition ended up working well :

...
interface Icontrol : IDispatch{
[ 
uuid(...), 
version(1.0) ] 
typedef struct fake
{ 
    int x;
    int y;
    int z;
} fake; 
[id(1)] HRESULT open_connection([out,retval] VARIANT_BOOL* result);
...

This does not answer the question of what to do if your type does not map 1:1 to a C# type, but at least I can use the C++ defined structures in C#.