Symptoms

PyWin32 is installed from pywin32-204.win32-py2.3.exe.
Using win32com.client to hook events in Visual
Studio .NET 2003, the following code fails:

-------- bugtest.py --------
from win32com.client.gencache import EnsureModule
from win32com.client import Dispatch

EnvDTE = EnsureModule( '{80CC9F66-E7D8-4DDD-
85B6-D9E6CD0E93E2}', 0, 7, 0 )
dte = Dispatch( 'VisualStudio.DTE' )
events = dte.Events
docEvents = events.DocumentEvents
print docEvents
-------- bugtest.py --------

The failure is as follows:

-------- traceback --------
Traceback (most recent call last):
File "C:\dev\PyAddin\BugTest.py", line 7, in -toplevel-
docEvents = events.DocumentEvents
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 455, in
__getattr__
return self._ApplyTypes_(*args)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 449, in
_ApplyTypes_
user, resultCLSID)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 467, in
_get_good_object_
return _get_good_object_(obj, obUserName,
resultCLSID)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 485, in
_get_good_object_
return _get_good_single_object_(obj, obUserName,
resultCLSID)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 472, in
_get_good_single_object_
return Dispatch(obj, obUserName, resultCLSID,
UnicodeToString=NeedUnicodeConversions)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 96, in
Dispatch
return __WrapDispatch(dispatch, userName,
resultCLSID, typeinfo, UnicodeToString, clsctx)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 40, in
__WrapDispatch
return klass(dispatch)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 490, in
__init__
self.__dict__["_dispobj_"] = self.default_interface(oobj)
File "C:\PROGRA~1\Python23\lib\site-
packages\win32com\client\__init__.py", line 495, in
__getattr__
d=self.__dict__["_dispobj_"]
KeyError: '_dispobj_'
-------- traceback --------

Cause

In genpy.py, _Build_CoClassChildren enumerates the
dispatchable interfaces of a coclass, to construct the
list of interfaces and dispinterfaces to be generated. But
some interfaces, though dispatchable, are not listed as
TKIND_DISPATCH (I think these are Automation
interfaces as opposed to Dual interfaces; this is just a
guess, though). These interfaces then don't get included
in the generated module. Listing the dispinterfaces for
DocumentEvents using the OLE object viewer that
comes with Visual Studio, versus inspecting the
generated Python coclass for DocumentEvents,
highlights the shortcoming.

Possible solution

Applying the following patch to genpy.py solves the
problem, allowing Visual Studio events to be hooked in
Python:

-------- diff --------
680c680,681
< if refAttr.typekind ==
pythoncom.TKIND_DISPATCH:
---
> if refAttr.typekind ==
pythoncom.TKIND_DISPATCH or \ > (refAttr.typekind ==
pythoncom.TKIND_INTERFACE and refAttr[11] &
pythoncom.TYPEFLAG_FDISPATCHABLE):
-------- diff --------

I have not tried to test whether this has any adverse
effects on other aspects of pythoncom. But the
additional data in the generated module seems to be
healthy.

Remarks

Visual Studio .NET has a different system of event
source objects from Office applications. Office
applications are their own event sources, whereas
Visual Studio .NET has several different event objects,
for Document events, Solution events, IDE events and
so on. I suppose this architectural difference is why this
bug appears not to have been reported against Office
applications too.