[python-win32] Accessing other interfaces of a Dispatch created COM object

[Alec Munro]

I'm guessing, based on the lack of responses, and the consistency of
error messages, that my problem has more to do with getting the right
library registered, which isn't a python-win job.

So, can anyone recommend where I might go to try to solve this
problem? Also, is there a way to determine which library it is that is
not registered?

Thanks again,

Alec

On Fri, Aug 29, 2008 at 2:47 PM, Alec Munro <alecmunro at gmail.com> wrote:
> Thanks Mark.
>
> After a couple of misfires, I think I figured out how to get CastTo to
> work (the docstring is practically non-existent in the version I have,
> perhaps it's been updated?).
>
> However, that puts me back at the same place I was with some of the
> other attempts:
>
>>>> obj_i2 = CastTo(obj, "Interface_2")
>>>> obj_i2.secondaryMethod()
> Traceback (most recent call last):
> ...
>  File "C:\Python25\lib\site-packages\win32com\client\__init__.py",
> line 449, in _ApplyTypes_
>   dispid, 0, wFlags, retType, argTypes, *args),
> com_error: (-2147319779, 'Library not registered.', None, None)
>
> However, one interesting note is that the object generated by CastTo
> is of a different version of the Type Library than the object
> generated by Interface_2(obj). I don't know if that's useful
> information, however. They have the same CLSID, but different
> coclass_clsids.
>
> Thanks again,
>
> Alec
>
> On Fri, Aug 29, 2008 at 3:01 AM, Mark Hammond <mhammond at skippinet.com.au> wrote:
>> Look at the docstring for win32com.client.CastTo (and googling for that will
>> probably help too)
>>
>> Cheers,
>>
>> Mark
>>
>>> I just discovered a third possibility, and subsequent failure:
>>>
>>> >>> obj_i2 = Dispatch(obj, None, Interface_2.CLSID)
>>> >>> obj_i2.secondaryMethod()
>>> Traceback (most recent call last):
>>> ...
>>>   File "C:\Python25\lib\site-packages\win32com\client\__init__.py",
>>> line 449, in _ApplyTypes_
>>>     dispid, 0, wFlags, retType, argTypes, *args),
>>> com_error: (-2147352573, 'Member not found.', None, None)
>>>
>>> Alec
>>>
>>> On Thu, Aug 28, 2008 at 10:33 AM, Alec Munro <alecmunro at gmail.com>
>>> wrote:
>>> > Oh, and on re-reading, I do realize that the DLL itself doesn't
>>> > implement those interfaces. There's a class within the DLL that does
>>> > that. :)
>>> >
>>> > On Thu, Aug 28, 2008 at 10:32 AM, Alec Munro <alecmunro at gmail.com>
>>> wrote:
>>> >> Hi List,
>>> >>
>>> >> Hopefully I have my terminology right, I'm pretty new to COM and
>>> C++.
>>> >>
>>> >> My problem is that I have a COM DLL written in C++, that I would
>>> like
>>> >> to call from Python. This DLL implements 3 important interfaces,
>>> each
>>> >> of which is also an IDispatch implementation, like the following:
>>> >>
>>> >> IDispatchImpl<Interface_1, &__uuidof(Interface_1),
>>> &LIBID_Interface_1, 1, 0>
>>> >> IDispatchImpl<Interface_2, &__uuidof(Interface_2),
>>> &LIBID_Interface_2, 1, 0>
>>> >> IDispatchImpl<Interface_3, &__uuidof(Interface_3),
>>> &LIBID_Interface_3 1, 0>
>>> >>
>>> >>  However, when I do:
>>> >>>>> obj = win32com.client.Dispatch("a.b.c")
>>> >>>>> obj
>>> >> <COMObject a.b.c>
>>> >>
>>> >> The object I get only has methods available for the first of the
>>> >> interfaces. From my reading, this is simply the functionality of
>>> >> IDispatch, and if I wanted to get those additional methods through
>>> >> IDispatch, I would have to update the DLL, and restructure my
>>> >> interfaces. I'm not confident enough in my C++ to do this, or at
>>> least
>>> >> it's not my first choice.
>>> >>
>>> >> From what I've read, there are two ways that seem to be
>>> possibilities
>>> >> for being able to call the methods from the other interfaces.
>>> >>
>>> >> The simplest one I found was the suggestion to use MakePy on the
>>> type
>>> >> library containing Interface_2 and Interface_3. I did this, and
>>> copied
>>> >> the generated file to my working directory, then did:
>>> >>
>>> >>>>> from interfaces import Interface_2
>>> >>>>> obj_i2 = Interface_2(obj)
>>> >>>>> obj_i2
>>> >> <win32com.gen_py.typelibname 1.0 Type Library.Interface_2 instance
>>> at
>>> >> 0x17459602>
>>> >>
>>> >> Unfortunately when I try:
>>> >>
>>> >>>>> obj_i2.secondaryMethod()
>>> >> Traceback (most recent call last):
>>> >> ...
>>> >>  File "C:\Python25\lib\site-packages\win32com\client\__init__.py",
>>> >> line 449, in _ApplyTypes_
>>> >>   dispid, 0, wFlags, retType, argTypes, *args),
>>> >> com_error: (-2147319779, 'Library not registered.', None, None)
>>> >>
>>> >> The other suggestion I came across was to use QueryInterface. I
>>> wasn't
>>> >> sure what argument to pass to QueryInterface, so I tried using the
>>> >> CLSID of the interface I wanted.
>>> >>
>>> >>>>> obj._oleobj_.QueryInterface(Interface_2.CLSID)
>>> >> Traceback (most recent call last):
>>> >>  File "<interactive input>", line 1, in <module>
>>> >> TypeError: There is no interface object registered that supports
>>> this IID
>>> >>
>>> >> From these error messages, it seems like perhaps there's a problem
>>> >> with the registration of the type library that contains the
>>> >> interfaces. I'm not really sure how to fix that, or if that is even
>>> >> the problem.
>>> >>
>>> >> Any ideas?
>>> >>
>>> >> Thanks,
>>> >> Alec Munro
>>> >>
>>> >
>>> _______________________________________________
>>> python-win32 mailing list
>>> python-win32 at python.org
>>> http://mail.python.org/mailman/listinfo/python-win32
>>
>>
>