Ruby problems calling VB COM using win32ole

Hi,

I’m experiencing some unusual behaviour trying to use VB COM through
win32ole in Ruby, and I’m hoping someone might be able to help. I’m
using Ruby 1.84-19 (final) here.

I’ve included the contents of the files I’m using to reproduce these
issues below. Note that you need VB6 to build the COM DLL, but hopefully
you’ll be able to see what it’s doing without this.

If you run the script, you’ll find that it calls a VB subroutine that
raises an error, and just before this it displays a dialog window saying
“About to raise error…”. However, despite the script only containing
one call to this subroutine, when you click OK to dismiss the window it
appears again. Is this a bug or is there an explanation for it?

The script then calls a VB function that returns an empty variant and an
uninitialised array in a variant. However, when Ruby tries to display
the contents of the return value it gives different results, namely
‘nil’ and ‘false’. I was expecting it to display ‘nil’ in both cases
since there is no data available, but perhaps I’ve misunderstood
something. Note that until the most recent version, this final call
would actually generate a segmentation fault!

Thanks,

Andrew.

Problems.rb


require ‘win32ole’

def problems()
begin
test = WIN32OLE.new(‘Project1.Class1’)
test.raiseerror()
end
rescue
puts test.emptyvariant()
puts test.emptyarray()
end

problems()

Class1.cls


VERSION 1.0 CLASS
BEGIN
MultiUse = -1 'True
Persistable = 0 'NotPersistable
DataBindingBehavior = 0 'vbNone
DataSourceBehavior = 0 'vbNone
MTSTransactionMode = 0 'NotAnMTSObject
END
Attribute VB_Name = “Class1”
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = True
Option Explicit
Public Function EmptyVariant() As Variant
End Function
Public Function EmptyArray() As Variant
Dim Test() As Variant
EmptyArray = Test
End Function
Public Sub RaiseError()
MsgBox “About to raise error…”
Err.Raise vbObjectError
End Sub

Project1.vbp


Type=OleDll
Class=Class1; Class1.cls
Reference=*\G{00020430-0000-0000-C000-000000000046}#2.0#0#C:\WINNT\System32\STDOLE2.TLB#OLE
Automation
Startup="(None)"
ExeName32=“Project1.dll”
Command32=""
Name=“Project1”
HelpContextID=“0”
CompatibleMode=“1”
CompatibleEXE32=“Project1.dll”
MajorVer=1
MinorVer=0
RevisionVer=0
AutoIncrementVer=0
ServerSupportFiles=0
VersionCompanyName=“BNP Paribas”
CompilationType=0
OptimizationType=0
FavorPentiumPro™=0
CodeViewDebugInfo=0
NoAliasing=0
BoundsCheck=0
OverflowCheck=0
FlPointCheck=0
FDIVCheck=0
UnroundedFP=0
StartMode=1
Unattended=0
Retained=0
ThreadPerObject=0
MaxNumberOfThreads=1
ThreadingModel=1

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