[python-win32] Passing Arrays by Reference

[Erignac, Charles A]

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
>
>
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>

-- 
Jens B. Jorgensen
jens.jorgensen@tallan.com

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