How to avoid self reference with IsWorkBookOpen - vba

Question

I wanted to use shared excel workbooks on server which would be variously connected to each other.
I worked on it for many days to only find out it has many problems to cope with as shared workbooks do not support many features.
I wanted the macro to check on opening the file to find out whether the file is opened by someone else and if "yes", it would tell the person to come back later.
Unfortunately, I am now referencing to myself and this creates a loop.
I open the file, it checks itself it is opened already and then after the message it closes.
Could you please help me to evade the loop so it would suit the purpose?
I believe only the upper part of the code relates to my problem, so I do not post it in full:
Option Explicit
Private Sub Workbook_Open()
Dim Ret
Ret = IsWorkBookOpen(ThisWorkbook.FullName)
If Ret = True Then
MsgBox "Come back later."
ThisWorkbook.Close savechanges:=False
End If
End Sub
Function IsWorkBookOpen(FileName As String)
Dim ff As Long, ErrNo As Long
On Error Resume Next
ff = FreeFile()
Open FileName For Input Lock Read As #ff
Close ff
ErrNo = Err
On Error GoTo 0
Select Case ErrNo
Case 0: IsWorkBookOpen = False
Case 70: IsWorkBookOpen = True
Case Else: Error ErrNo
End Select
End Function

Answer 1

I don't think you need to use that function for your purpose.
You can actually check the status of the file using:
ThisWorkbook.ReadOnly
which returns a boolean; true if file is readonly.
Now, before opening the file you really cannot suppress the pop up asking if you want to open it as read only or not. But you can still try putting this code which will trigger once the user opened the file as read only.
Private Sub Workbook_Open()
If ThisWorkbook.ReadOnly Then
MsgBox "Comeback some other time. File in use"
ThisWorkbook.Close False
End If
End Sub
Private Sub Workbook_BeforeClose(Cancel As Boolean)
Application.Quit
End Sub

Answer 2

The beauty of the IsWorkBookOpen approach is the speed compared to opening the workbook over a network compared to a ReadOnly test.
I would recommend you change your approach to load the check from a vbs, or a separate Excel file - as this is the best method.
The code below can be save in NotePad on your network drive as a vbs, say check.vbs. The code checks if the file is open, if not then it launches the file in a new instance of Excel. If it is, a message is provided.
vbs code
Dim objExcel
FileName = "C:\temp\file.xlsm"
If Not IsWorkBookOpen(FileName) Then
Set objExcel = CreateObject("Excel.Application")
Set ojbWb = objExcel.Workbooks.Open(FileName)
objExcel.Visible = True
Else
wscript.echo FileName & " already opened"
End If
Function IsWorkBookOpen(FileName)
Set oFSO = CreateObject("Scripting.FileSystemObject")
On Error Resume Next
Set objFile = oFSO.OpenTextFile(filename, 8, False)
ErrNo = Err
ObjFile.Close
On Error GoTo 0
Select Case ErrNo
Case 0: IsWorkBookOpen = False
Case 70: IsWorkBookOpen = True
Case Else: Error ErrNo
End Select
set objFSO = Nothing
End Function
If you want to run the check from the actual file then you will need to change to the ReadOnly test
code
Private Sub Workbook_Open()
If Me.ReadOnly Then MsgBox "file already opened", vbCritical
End Sub

Answer 3

I post this as I have seen this question unanswered on other forums, too.
I wanted to use many shared excel workbooks on server which would be variously connected to each other.
I wanted to use the so called shared workbook so everyone could access it and especially for the reason that it would track the changes within (users, time,...)
I wanted the macro to check on opening the file to find out whether the file is opened by someone else and if "yes", it would tell the person to come back later.
Suggested replies here could not help and I believe there is no chance to create a macro for path of the file itself so that IsWorkBookOpen(ThisWorkbook.FullName)
could be used the way I tried.
I decided to write macro that would track changes within the Workbook as if it was "shared". This way I was able to "unshare" it and use the ReadOnly approach discussed here.