[python-win32] vb errors from Python COM object now include the traceback lines

Lloyd Kvam python at venix.com
Fri Apr 20 13:42:03 CEST 2012

On Fri, 2012-04-20 at 15:52 +1000, Mark Hammond wrote:
> On 20/04/2012 8:30 AM, Lloyd Kvam wrote:
> > On Thu, 2012-04-19 at 16:32 -0400, Lloyd Kvam wrote:
> >> I am hoping one of you can point me in the right direction.  My
> >> alternative appears to be (painfully) writing some VB code to discard
> >> the traceback lines from  Err.Description.
> Hrm - I thought it had always been the case that if you throw an 
> explicit COMException, then you shouldn't get the traceback - the 
> traceback only appears for "other" exceptions, which presumably indicate 
> the exception was unintended.

The COMException is the code I added.  Up until now I had not translated
the Python exceptions into COMExceptions.  This had worked OK.

> >
> > I read more carefully through Python Programming on Win32 and came up
> > with this code:
> >
> > """"""""""""""""""""""""""""""""""""""""""""""""""""""""""
> > class DefaultDebugDispatcher(
> > 	win32com.server.dispatcher.DefaultDebugDispatcher):
> >      def _HandleException_(self):
> >          excls,exself = sys.exc_info()[:2]
> >          if not IsCOMServerException(excls):
> >              raise COMException(description = str(exself),
> >                  scode = winerror.E_INVALIDARG,
> >                  )
> Which seems to backup my point - IsCOMServerException() is returning 
> false, so the exception isn't a COMException, so you turn it into one 
> and avoid the traceback etc.
> Note however that you could just also raise a COMException directly from 
> the original point - ie, there should be no need to convert to a 
> COMException if a COMException is thrown in the first place.

The original code is meant to run on any supported OS.  It's just normal
Python.  I do my development work using Linux.  The COM object is
created by simply using a module to wrap the application into a COM
object using the pywin32 services.  Up until now, the Python exceptions
with their error messages simply percolated up to the VB GUI.

> How are you throwing the original?  If you thought you were throwing a 
> COMException then we would want to check you actually are if you still 
> think so, dig into why IsCOMServerException is failing.
> Cheers,
> Mark

Thank you very, very much for your efforts integrating Python and
Windows.  The core application is around 14,000 lines of code.  The
wrapper module to turn it into a COM object for deployment in Windows is
just under 600 lines.

Lloyd Kvam
Venix Corp

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