Why is this an issue?
Generally, writing the least code that will readably do the job is a good thing, so omitting default parameter values seems to make sense.
Unfortunately, when you omit them from the base call in an override, you’re not actually getting the job done thoroughly, because you’re
ignoring the value the caller passed in. The result will likely not be what the caller expected.
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
