Why is this an issue?
When optional parameter values are not passed to base method calls, the value passed in by the caller is ignored. This can cause the function to
behave differently than expected, leading to errors and making the code difficult to debug.
How to fix it
Code examples
Noncompliant code example
Public Class BaseClass
Public Overridable Sub MyMethod(ByVal Optional i As Integer = 1)
Console.WriteLine(i)
End Sub
End Class
Public Class DerivedClass
Inherits BaseClass
Public Overrides Sub MyMethod(ByVal Optional i As Integer = 1)
' ...
MyBase.MyMethod() ' Noncompliant: caller's value is ignored
End Sub
Private Shared Function Main(ByVal args As String()) As Integer
Dim dc As DerivedClass = New DerivedClass()
dc.MyMethod(12) ' prints 1
End Function
End Class
Compliant solution
Public Class BaseClass
Public Overridable Sub MyMethod(ByVal Optional i As Integer = 1)
Console.WriteLine(i)
End Sub
End Class
Public Class DerivedClass
Inherits BaseClass
Public Overrides Sub MyMethod(ByVal Optional i As Integer = 1)
' ...
MyBase.MyMethod(i)
End Sub
Private Shared Function Main(ByVal args As String()) As Integer
Dim dc As DerivedClass = New DerivedClass()
dc.MyMethod(12) ' prints 12
End Function
End Class
Resources
Documentation
Microsoft Learn - Optional Arguments
(Visual Basic)
