VBA: Sub to Write to a Log File - vba

Question

I have a set of macros defined in my workbook, and I'd like to offer the user the option to log events related to those macros in a log file.
I initiate the log by creating the following in ThisWorkbook:
Public writeLog as Boolean
Public logWrite as Object
Public log as Object
Private Sub Worksheet_Open()
Dim prompt as Integer
prompt = MsgBox("Would you like to log events for this session?", vbYesNo, "Log Events?")
If prompt Then
writeLog = True
Set logWrite = CreateObject("Scripting.FileSystemObject")
Set log = logWrite.CreateTextFile("C:/TEST.txt", False)
Else
writeLog = False
End If
End Sub
I then created a procedure that I can use to write an argument to this object, which I've stored in its own module:
Public Sub PrintLog(obj as Object, argument as String)
If writeLog = True Then
obj.WriteLine argument
End If
End Sub
Unfortunately, this doesn't work, and I'm not sure why: even if I don't include obj as an argument to the function (since log and logWrite were created as global variables), I'm not able to Call WriteLog("String here.") or Call WriteLog(log, "String here.") without an error (Compile Error: Argument Not Optional.)
Is it possible to get such a Sub() to work, so that I can call it from anywhere in the workbook (after a button is pressed in a userform, for example) without having to define a new Scripting.FileSystemObject in every module?

Answer 1

I think that you can solve your problem by making some minor changes to your code. I tried the following setup:
logger module:
Option Explicit
Private log As Object
Public Sub initLog()
Dim prompt As VbMsgBoxResult
Dim fso As Object
prompt = MsgBox("Would you like to log events for this session?", vbYesNo, "Log Events?")
If prompt = vbYes Then
Set fso = CreateObject("Scripting.FileSystemObject")
Set log = fso.CreateTextFile("C:/TEST.txt", False)
End If
End Sub
Public Sub PrintLog(argument As String)
If Not log Is Nothing Then
log.WriteLine argument
End If
End Sub
Public Sub yadda()
'test
PrintLog "yadda"
End Sub
ThisWorkbook:
Private Sub Workbook_Open()
initLog
End Sub

Answer 2

This is my no-frills drop in replacement for Debug.Print(), that logs to "Log.txt" at your Workbook path.
To install : Just search and replace "Debug.Print" with "Log", and optionally call LogClear() at the start of your program.
Public Function Log(ByRef a_stringLogThis As String)
' send to TTY
Debug.Print (a_stringLogThis)
' append (not write) to disk
Open ThisWorkbook.path & "\Log.txt" For Append As #1
Print #1, a_stringLogThis
Close #1
End Function
OPTIONAL : And here's a helper you COULD call at the beginning of your to clear out the previous logs.
Public Function LogClear()
Debug.Print ("Erasing the previous logs.")
Open ThisWorkbook.path & "\Log.txt" For Output As #1
Print #1, ""
Close #1
End Function
OPTIONAL : Finally, if can't live without date and time in your logging, use this Log statement instead:
Public Function Log(ByRef a_stringLogThis As String)
' prepare date
l_stringDateTimeNow = Now
l_stringToday = Format(l_stringDateTimeNow, "YYYY-MM-DD hh:mm:ss")
' concatenate date and what the user wants logged
l_stringLogStatement = l_stringToday & " " & a_stringLogThis
' send to TTY
Debug.Print (l_stringLogStatement)
' append (not write) to disk
Open ThisWorkbook.path & "\Log.txt" For Append As #1
Print #1, l_stringLogStatement
Close #1
End Function

Answer 3

I believe you're having issues as writeLog already exists as a boolean. Error should be popping up "Ambiguous name detected"
Try the following,
Public bLog as Boolean
Public logWrite as Object
Public log as Object
Private Sub Worksheet_Open()
Dim prompt as Integer
prompt = MsgBox("Would you like to log events for this session?", vbYesNo, "Log Events?")
If prompt Then
bLog = True
Set logWrite = CreateObject("Scripting.FileSystemObject")
Set log = logWrite.CreateTextFile("C:/TEST.txt", False)
Else
bLog = False
End If
End Sub
Public Sub WriteLog(Optional obj as Object, Optional argument as String)
If bLog = True Then
obj.WriteLine argument
End If
End Sub
Edit: made parameters optional in WriteLog (or PrintLog) for further testing

Answer 4

' Write to a log file using Separator and Array of variant Parameters
' Auto generate the file
' USE EndLog to close
'use:
' PrintLog vbtab, "one", 2, 3
' PrintLog vbtab, "Apple","Windows","Linux","Android","Commodore","Amiga","Spectrum"
' EndLog
' Generate a csv file:
' PrintLog ";", rst!ID, rst!Name
Private FileLog As Object
Private fso As Object
Const DEBUG_LOG_FILE = "C:\log.txt"
Public Sub PrintLog(ByVal Separator As String, ParamArray Arguments() As Variant)
Dim ele As Variant
Dim line As String
If FileLog Is Nothing Then
Set fso = CreateObject("Scripting.FileSystemObject")
Set FileLog = fso.CreateTextFile(DEBUG_LOG_FILE, True, True)
End If
line = CStr(Now()) ' Print Timestamp
For Each ele In Arguments
If line > "" Then line = line & Separator
line = line & CStr(ele)
Next
If line > "" Then FileLog.WriteLine line
End Sub
Public Sub EndLog()
On Error Resume Next
FileLog.Close
Set FileLog = Nothing
Set fso = Nothing
On Error GoTo 0
End Sub