[python-win32] Input-only vs. In/Out Function Parameters

[Smith, Brian (CR)]

Hi Mark,

> > 2) VBA was giving me an error like "Expecting 3 return values, got: 2"
> > whenever a function contained an [in, out] parameter.  It looks like the
> > extra parameter it is looking for is the HRESULT signifying the success
of
>
> There should be no need to return a HRESULT - but note that the nominated
> return value must be the *first* value returned, with [out] params
following
> in the order they were declared.

That's what I would have expected.  In fact, this is the case if I don't use
a type library.  However, when using a type library I have to return it
*last* for the object to work from VBA.

> As a result, method4 really should only need 2 return values - I'm not
sure
> why it seems to want more.  If you can provide a patch to the pippo sample
> that demonstrates your problem I can dig deeper.

The patches are below.  I added two methods with the same signature.  The
difference is that Method2() returns two values (as the IDL signature would
suggest) and Method3() returns 3 values, with a 0 as the first value.  My
VBA test code (also attached) calls Method3() first and correctly sets
inout1 to -31 and the return value to -41.  Note that this occurs even
though the nominated return value is the *last* return value.  The call to
Method2() fails with the "Expecting 3 return values, got: 2" error.

My platform is Win XP Pro (SP2), Python 2.3.4, pywin Build 210.  I'm testing
using VBA in MS Excel 2000.

Thanks,
Brian


---- pippo.idl patch begin ----
32a33,36
>         [id(3), helpstring("method Method2")] HRESULT Method2([in] long
in1, [in, out] long *inout1,
>                 [out, retval] long *val);
>         [id(4), helpstring("method Method3")] HRESULT Method3([in] long
in1, [in, out] long *inout1,
>                 [out, retval] long *val);
---- pippo.idl patch end ----


---- pippo_server.py patch begin ----
35a36,45
>     def Method2(self, in1, inout1):
>         new_inout1 = -31
>         retVal = -41
>         return( new_inout1, retVal )
>
>     def Method3(self, in1, inout1):
>         new_inout1 = -31
>         retVal = -41
>         return( 0, new_inout1, retVal )
>
---- pippo_server.py patch end ----


---- VBA test code begin ----

Sub TestPippo()
    Dim obj As Pippo
    Dim in1 As Long
    Dim inout1 As Long
    Dim before As String
    Dim after As String

    Set obj = CreateObject("Python.Test.Pippo")
    in1 = 3
    inout1 = 5
    before = "in1 = " + CStr(in1) + ", inout1 = " + CStr(inout1)
    retVal = obj.Method3(in1, inout1)
    after = "in1 = " + CStr(in1) + ", inout1 = " + CStr(inout1) + ", retVal
= " + CStr(retVal)
    MsgBox before + vbCrLf + after, , "Testing Method3"
   
    in1 = 3
    inout1 = 5
    before = "in1 = " + CStr(in1) + ", inout1 = " + CStr(inout1)
    retVal = obj.Method2(in1, inout1)
    after = "in1 = " + CStr(in1) + ", inout1 = " + CStr(inout1) + ", retVal
= " + CStr(retVal)
    MsgBox before + vbCrLf + after, , "Testing Method2"
    Set obj = Nothing
End Sub

---- VBA test code end ---- 
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