Why is this an issue?
A typical code smell known as unused function parameters refers to parameters declared in a function but not used anywhere within the function’s
body. While this might seem harmless at first glance, it can lead to confusion and potential errors in your code. Disregarding the values passed to
such parameters, the function’s behavior will be the same, but the programmer’s intention won’t be clearly expressed anymore. Therefore, removing
function parameters that are not being utilized is considered best practice.
This rule raises an issue when a private procedure of a Class, Module or Structure takes a
parameter without using it.
Exceptions
This rule doesn’t raise any issue in the following contexts:
- Procedures decorated with attributes.
- Empty procedures.
- Procedures which only throw
NotImplementedException.
- Main methods.
-
virtual, override procedures.
- Interface implementations.
- Event handlers.
How to fix it
Having unused function parameters in your code can lead to confusion and misunderstanding of a developer’s intention. They reduce code readability
and introduce the potential for errors. To avoid these problems, developers should remove unused parameters from function declarations.
Code examples
Noncompliant code example
Private Sub DoSomething(ByVal a As Integer, ByVal b as Integer) ' "b" is unused
Compute(a)
End Sub
Private Function DoSomething2(ByVal a As Integer, ByVal b As Integer) As Integer ' "a" is unused
Compute(b)
Return b
End Function
Compliant solution
Private Sub DoSomething(ByVal a As Integer)
Compute(a)
End Sub
Private Function DoSomething2(ByVal b As Integer) As Integer
Compute(b)
Return b
End Function
