[python-win32] Passing Arrays by Reference

[Mark Hammond]

If someone is really keen, we could get this fixed once and for all in
win32com.  In the win32com\test directory, testvb.py does all sorts of funky
argument passing between Python and VB, including arrays.  Obviously not all
array combinations it would seem <wink>.

The VB side of this component is in the win32com source tree, or mail me for
it (it is pretty small).

Then if we can keep the existing semantics (which are obviously correct for
byval arrays or some such) but also demonstrate this specific problem, then
I will be able to find and fix the code responsible.

Mark.

> -----Original Message-----
> From: python-win32-admin@python.org
> [mailto:python-win32-admin@python.org]On Behalf Of Jens B. Jorgensen
> Sent: Friday, 8 November 2002 5:37 AM
> To: Erignac, Charles A
> Cc: 'python-win32@python.org'
> Subject: Re: [python-win32] Passing Arrays by Reference
>
>
> And that makes it work?! Whoa. Weird.
>
> Erignac, Charles A wrote:
>
> >I used Jens's example below to check that I could pass a python array by
> >reference to a vb method that modifies it. I also checked that the
> >CATIA.Position.GetComponents call that failed to modify the
> array passed by
> >reference in python actually works from vb.
> >So as a quick fix I created a vb proxy that places the call on behalf of
> >python. It is not elegant but it works. This is what the proxy
> looks like:
> >
> >Public Sub GetComponents(o As Object, ByRef a() As Variant)
> >  o.GetComponents a
> >End Sub
> >
> >Charles
> >
> >-----Original Message-----
> >From: Jens B. Jorgensen [mailto:jens.jorgensen@tallan.com]
> >Sent: Wednesday, November 06, 2002 1:04 PM
> >To: Erignac, Charles A
> >Cc: 'python-win32@python.org'
> >Subject: Re: [python-win32] Passing Arrays by Reference
> >
> >
> >Things seem to work fine for me. I created a test ActiveX DLL in VB with
> >a single object. Here's the code for it:
> >
> >Public Sub DoArrayThing(larr() As Long)
> >  Dim i As Long
> >  For i = LBound(larr) To UBound(larr)
> >    larr(i) = larr(i) + 1
> >  Next i
> >
> >End Sub
> >
> >Then in python here's what I get:
> >
> >ActivePython 2.2.1 Build 222 (ActiveState Corp.) based on
> >Python 2.2.1 (#34, Apr 15 2002, 09:51:39) [MSC 32 bit (Intel)] on win32
> >Type "help", "copyright", "credits" or "license" for more information.
> > >>> from win32com.client import Dispatch
> > >>> o = Dispatch('TestArray.ArrManip')
> > >>> o.DoArrayThing(range(0, 4))
> >(1, 2, 3, 4)
> > >>> a = _
> > >>> o.DoArrayThing(a)
> >(2, 3, 4, 5)
> > >>>
> >
> >So it looks like everything python is doing is all fine and good with
> >the arrays.
> >
> >Erignac, Charles A wrote:
> >
> >
> >
> >>I am calling a method on a COM object that fills in an array passed by
> >>reference. The array must be initialized to a given size
> otherwise the call
> >>will fail. Currently I am able to complete the call and the
> array returned
> >>by the method is the one I passed as a parameter but unfortunately the
> >>
> >>
> >value
> >
> >
> >>of the array does not change and it should. For your information the COM
> >>object I work with is a Position interface maintained by the CATIA COM
> >>server. The method is Sub GetComponents(CATSafeArrayVariant array). I
> >>understand that the CATSafeArrayVariant type is equivalent to
> an array of
> >>variants.
> >>The python call looks like this:
> >>	a = range(0,12)
> >>	b = myPosition.GetComponents(a)
> >>	print a # outputs (0,1,2,3,4,5,6,7,8,9,10,11) instead of the actual
> >>components
> >>	print b # same output
> >>
> >>The call is an early binding thanks to pygen.
> >>I would appreciate any help regarding this problem. I would
> like at least
> >>
> >>
> >to
> >
> >
> >>know where to look in the win32com code to understand what is
> going wrong.
> >>Best regards,
> >>
> >>Charles
> >>
> >>
> >>_______________________________________________
> >>Python-win32 mailing list
> >>Python-win32@python.org
> >>http://mail.python.org/mailman/listinfo/python-win32
> >>
> >>
> >>
> >>
> >
> >
> >
>
> --
> Jens B. Jorgensen
> jens.jorgensen@tallan.com
>
> "With a focused commitment to our clients and our people, we
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