## 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