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Making dataset instances invisible to COM

Hi There,

I've got a C# assembly that's marked for COM Interop Registration.  It contans a dataset definition (.xsd file in the Visual Studio IDE).  When I look at the TLB file generated for the assembly, there's a bunch of objects from the dataset included.  (for example, if the dataset is called AlphaDS, there's a default interface generated for the dataset called _AlphaDS, and a coclass entry for AlphaDS, plus default objects for the tables, rows and events defined in the dataset)

I'd like to mark the Dataset as COMVisible(false) so it doesn't show up in the TLB.  I could mark the generated .cs file for the dataset with this attribute, but this file is auto-generated and the changes are lost each time I re-build the assembly.  

Anyone have any ideas?

1 Solution
afuchigamiAuthor Commented:
After some research and discussion on different forums, we figured out a solution.  Here's what we found for anyone who runs into this issue.

In VS2005, DataSet objects are marked as partial classes.  You could define another partial class for each Dataset object and mark it as COMVisible(false).  When the code is compiled, the completed Dataset object would get the COMVisible(false) attribute setting.

In VS2003 (and later), you can mark an entire assembly as not being visible to COM with the following attribute:  [assembly:ComVisible(false)]
When you do this, you have to explicitly mark all the classes/interfaces that you want visible to COM as COMVisible(true).  This is different from the default behaviour where each public object is visible to COM when this assembly attribute was not set.  Using this method, all the dataset objects are invisible to COM.

A different option would be to move all the datasets into a separate assembly that isn't used for COM Interop.

Note - the 'Register for COM Interop' option in Visual Studio isn't an assembly property - it's a post-build action performed by the Visual Studio IDE.


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