[python-win32] issues with win32com constants and static/dynamicdispatch

[Mark Hammond]

That is strange - the problem is that the resulting COM object is returning
an IUnknown rather than an IDispatch.  A work around should be to say:

c = cams[0]
c = win32com.client.Dispatch(c)

or possibly:

c = win32com.client.Dispatch(c.QueryInterface(pythoncom.IID_IDispatch))

I think we could also argue this is a bug in win32com - it should try and QI
any IUnknown objects - but changing this might break existing code...

Mark
  -----Original Message-----
  From: python-win32-bounces at python.org
[mailto:python-win32-bounces at python.org]On Behalf Of Jason Ferrara
  Sent: Thursday, 5 July 2007 12:30 AM
  To: python-win32 at python.org
  Subject: [python-win32] issues with win32com constants and
static/dynamicdispatch


  I'm trying to use a COM library from python.


  If I use dynamic dispatch, the com objects all behave correctly, but the
constants defined in the COM library don't show up.


  If I use static dispatch, the constants show up, but COM objects returned
by calls into the COM library seem broken.


  As example, starting with dynamic dispatch


    Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bit
(Intel)] on win32
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import win32com.client
    >>> mi=win32com.client.Dispatch("MIDLIBCom.MIDLib")
    >>> cams=mi.OpenCameras("C:\Program Files\Micron Imaging\sensor_data")
    >>> c=cams[0]
    >>> print c
    <COMObject OpenCameras>
    >>> print c.productName
    Micron Imaging DEMO2


  So far everything is fine, but now...


    >>> print win32com.client.constants.MI_BAYER_8
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "C:\Python25\Lib\site-packages\win32com\client\__init__.py", line
168, in
     __getattr__
        raise AttributeError, a
    AttributeError: MI_BAYER_8


  This is no good. So now I try static dispatch


    Python 2.5.1 (r251:54863, Apr 18 2007, 08:51:08) [MSC v.1310 32 bit
(Intel)] on win32
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import win32com.client
    >>> mi=win32com.client.gencache.EnsureDispatch("MIDLIBCom.MIDLib")
    >>> print win32com.client.constants.MI_BAYER_8
    1


  Things are looking better, but now...


    >>> cams=mi.OpenCameras("C:\Program Files\Micron Imaging\sensor_data")
    >>> c=cams[0]
    >>> print c
    <PyIUnknown at 0xac640c with obj at 0xf0d808>
    >>> print c.productName
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: 'PyIUnknown' object has no attribute 'productName'




  So whats going on here? What am I doing wrong?


  Thanks


  - J








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