How to debug COM objects?

Question

C++ / C#

I use the OLE extension of the native windows clipboard (to be able to save pictures without loading the virtual memory of the process). This extension uses COM technology, namely, it requires that the inserted object implement the IDataObject interface. After the implementation of such an interface, the question arose, how can such objects be debugged at all? a simple example, after saving this object to the clipboard, I try to extract it and use the interface methods, and these methods do not work correctly - they give errors that cannot even occur in my implementation, in general I can’t understand what kind of code is being executed at all.

Answer 1

OutputDebugString + debugmonitor.
Or attach a debugger to the process that loaded the dll that implements your object and set breakpoints in your functions.