GPF in Excel COM app.

[Calvin H. Chipman]

What's wrong with this PBWin9 code? I'm running this on Windows XP with Excel 12. The include file was created by using PowerBASIC COM Browser. The program consistently GPF's when getting to the following code line:

oExcelRange.FormulaR1C1(0) = vVnt

Am I doing something wrong or is something not functioning correctly?

If I run the same code on Windows Vista with Excel 8 and a properly updated include file, I get an error 99 (Object Error) on the following code line:

oExcelApp.Visible(0) = 1

By the way, I'm specifically trying to use the direct interface.

#Compile Exe
#Dim All

#Include ".\Excel_PB9.inc"

Function PBMain () As Long
    Dim oExcelApp       As Int__Application
    Dim oExcelWorkbook  As Int__Workbook
    Dim oExcelRange     As IRange
    Dim vVnt            As Variant

    oExcelApp = NewCom $PROGID_Excel_Application
    If IsFalse IsObject(oExcelApp) Then
        MsgBox "Cannot get object: oExcelApp"
        Exit Function
    End If

    oExcelApp.Visible(0) = 1

    oExcelWorkBook = oExcelApp.Workbooks.Add()
    If IsFalse IsObject(oExcelWorkbook) Or Err Then
        MsgBox("Excel could not open workbook.")
        GoTo Terminate
    End If

    oExcelRange = oExcelApp.ActiveCell
    If IsFalse IsObject(oExcelRange) Or Err Then
        MsgBox("Excel could not set range.")
        GoTo Terminate
    End If
    vVnt = "Sample Text"
    '-----------------------------
MsgBox "Pause before setting text"
    'Here's where the GPF happens.
    oExcelRange.FormulaR1C1(0) = vVnt
MsgBox "Pause after setting text"
    '-----------------------------

    oExcelWorkbook.Close
    oExcelApp.Quit

    MsgBox "Finished"


Terminate:
    Let oExcelRange     = Nothing
    Let oExcelWorkbook  = Nothing
    Let oExcelApp       = Nothing
End Function

Thanks,
Calvin

[José Roca]

You can not use Excel with direct interface calls. Only a few interfaces will work properly.

oExcelRange = oExcelApp.ActiveCell

doesn't return a reference to the IRange interface, but to the Range dispatch interface, that can only be used with OBJECT CALL/GET...

[Calvin H. Chipman]

Thanks José.

How do you determine what can use the direct interface and what cannot?

[José Roca]

If there are interfaces with virtual tables, you can call them using direct interface calls. But Excel is an oddity: it has a mix of dual interfaces, dispatch only interfaces and dispatchable interfaces, and the last ones can't be used with direct interface calls because any method or property returns a reference to them.

In the case of the ActiveCell property, look at the declaration:

Property Get ActiveCell <305> () As [B]Range[/B]

It returns a reference to the Range dispatch interface, not to the IRange interface.