Optional Parameters in python COM

Mark Hammond mhammond at skippinet.com.au
Tue Jan 27 23:25:01 CET 2004

Rane Bowen wrote:

> Hi,
> I am using python with a makepy generated wrapper on a COM application. One
> of this object's methods has 3 parameters, two of which are optional.
> If I call the method with just the non-optional parameter, or all three
> parameters, it works.  If I call it with the first two parameters, I get the
> following error:
> (-2147352567, 'Exception occurred.', (0, 'Amphora.Session.1', 'A bad
> parameter was passed to the method', None, 0, -1610547133), None)
> I have tried calling the method by using the names of the optional
> parameters, and I have also tried using pythoncom.Missing and
> pythoncom.Empty for the non essential parameter.  I have also edited the
> generated .py file so that it contains the following:
> defaultNamedOptArg=pythoncom.Empty
> defaultNamedNotOptArg=pythoncom.Empty
> defaultUnnamedArg=pythoncom.Empty
> But this has not made any difference!  Any help would be very much
> appreciated.

Can you reproduce this problem with a "common" object, such as IE, 
MSOffice, or a trivial VB object with sourcecode?  The problem is that 
it is up to each object to implement optional params, so it is very hard 
to pinpoint bugs in win32com here.


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