Visual Basic for Applications:
Writing to standard error

How to:

In VBA, since there’s no direct built-in function to write specifically to standard error like in some other programming languages, a common workaround involves using Debug.Print for development error output or creating a custom logging function that mimics this behavior for production applications. Below is an example of how you might implement and use such a function:

Sub WriteToErrorLog(msg As String)
    ' Custom function to simulate writing to standard error
    ' In actual deployment, this could write to a separate log file or a dedicated debugging window
    Open "ErrorLog.txt" For Append As #1 ' Change "ErrorLog.txt" to your desired log file path
    Print #1, "ERROR: " & msg
    Close #1
    Debug.Print "ERROR: " & msg ' Also output to Immediate Window in IDE for developer's debugging
End Sub

Sub Demonstration()
    ' Example usage of the WriteToErrorLog function
    WriteToErrorLog "An error occurred while processing your request."
End Sub

Sample output in “ErrorLog.txt” might look like this:

ERROR: An error occurred while processing your request.

And in the Immediate Window in the VBA IDE:

ERROR: An error occurred while processing your request.

Deep Dive

Visual Basic for Applications does not inherently include a dedicated mechanism for writing to standard error due to its deeply integrated nature with host applications like Excel, Word, or Access, which traditionally rely on graphical user interfaces rather than console output. This is a notable divergence from console-based applications typically developed in languages like C or Python, where standard output and standard error streams are fundamental concepts.

Historically, VBA’s focus has always been more on interacting with the document models of its host applications and less on traditional application logging mechanisms. Therefore, developers often resort to implementing custom logging solutions, as seen in the example, or utilizing Windows API calls for more advanced error handling and logging needs.

While the approach demonstrated provides a workaround, developers looking for more robust logging and error handling might explore integrating with external systems or libraries capable of more sophisticated logging. In modern development, especially with a focus on debugging and maintenance, the importance of clear, contextual, and separate logging of standard and error outputs cannot be overstated, pushing many to look beyond VBA’s native capabilities for solutions.