Visual Basic for Applications:
Refactoring

How to:

Consider a basic example in Visual Basic for Applications (VBA) where we have a subroutine that prints details of an employee. Initially, the code is cluttered, challenging to maintain, or extend.

Sub PrintEmployeeDetails()
    Dim name As String
    Dim age As Integer
    Dim department As String
    name = "John Doe"
    age = 30
    department = "IT"
    
    MsgBox "Name: " & name & vbCrLf & "Age: " & age & vbCrLf & "Department: " & department
End Sub

Refactoring step 1: Extract method. One of the most common refactoring techniques is to take a specific piece of code and move it into its own method. This makes the code more modular and easier to understand.

Sub PrintEmployeeDetails()
    Dim name As String
    Dim age As Integer
    Dim department As String
    name = "John Doe"
    age = 30
    department = "IT"
    
    DisplayMessage name, age, department
End Sub

Private Sub DisplayMessage(name As String, age As Integer, department As String)
    MsgBox "Name: " & name & vbCrLf & "Age: " & age & vbCrLf & "Department: " & department
End Sub

Refactoring step 2: Use a structure. This step involves using a data structure to hold related data, improving code clarity and making it easier to pass around grouped data.

Type Employee
    name As String
    age As Integer
    department As String
End Type

Sub PrintEmployeeDetails()
    Dim emp As Employee
    emp.name = "John Doe"
    emp.age = 30
    emp.department = "IT"
    
    DisplayMessage emp
End Sub

Private Sub DisplayMessage(emp As Employee)
    MsgBox "Name: " & emp.name & vbCrLf & "Age: " & emp.age & vbCrLf & "Department: " & emp.department
End Sub

These steps transform cluttered code into modular, structured code, significantly improving readability and maintainability.

Deep Dive

The concept of refactoring is as old as programming itself, but it was Martin Fowler’s book “Refactoring: Improving the Design of Existing Code” that brought it into the mainstream, emphasizing its importance in the software development process. In Visual Basic for Applications, refactoring can be somewhat more challenging due to the lack of built-in tools found in more modern integrated development environments (IDEs) that support automated refactoring.

However, this doesn’t diminish its importance. Even in VBA, applying basic refactoring techniques manually can greatly enhance the code base, making it cleaner and more efficient. While VBA may not have the same modern conveniences, the principles of good code design remain universal. Developers coming from other languages might find the manual process tedious but will undoubtedly appreciate the benefits of investing time in improving code quality from the onset.

For more robust development environments or when working on particularly sophisticated projects, it might be worth exploring alternatives that offer more powerful refactoring tools or converting VBA projects to a .NET language where Visual Studio provides extensive refactoring support. Nonetheless, understanding and applying refactoring principles in VBA is a valuable skill that underscores the importance of writing clean, maintainable code, no matter the environment.