[pywin32-bugs] [ pywin32-Bugs-985980 ] pywin32 custom i/f COM servers do not support variable or op

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Bugs item #985980, was opened at 2004-07-06 13:40
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https://sourceforge.net/tracker/?func=detail&atid=551954&aid=985980&group_id=78018

Category: com
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Phil Rittenhouse (prittenh)
Assigned to: Nobody/Anonymous (nobody)
Summary: pywin32 custom i/f COM servers do not support variable or op

Initial Comment:
I have discovered a couple of problems with the way 
the universal gateway code handles optional 
parameters and variable argument lists in COM servers.

It appears to only be a problem when you use the 
custom interface. 

What I found was that variable argument lists are not 
detected at all.  Instead they are just converted from 
SAFEARRAYs to a Python list.

Similarly, omitted optional parameters (which are sent 
by COM as VARIANTs with value of 
DISP_E_PARAMNOTFOUND) are converted to Python 
integers with the integer value of 
DISP_E_PARAMNOTFOUND.

I have made changes to univgw_dataconv.cpp to fix 
these problems but before I submit a patch, I'd like to 
make sure the changes make sense.  To fix the optional 
argument problem, the code now checks VT_VARIANTS 
to see if they are VT_ERRORs with the value 
DISP_E_PARAMNOTFOUND.  If they are, the argument 
is dropped, and presumably the Python method will 
have a suitable default to use in its place.

The variable argument code was a little more tricky.  I 
couldn't see any easy way to test if a method had the 
vararg property set, so I just assumed that any pointer 
to a SAFEARRAY of VARIANTS used as the last 
argument must represent a variable argument list.  It 
then converts the array and expands the parameter 
tuple to fit the new arguments.


Finally, I made a change to universal.py to handle the 
case where the variable argument list SAFEARRAY is 
declared [in, out] (as opposed to just [in]).  This was 
required to support VB.  In _GenerateOutArgTuple() I 
check if the method is a variable argument method and 
if so, I remove the variable arg parameter from the list 
of outputs.



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