Setting properties differently in child Class.

Public Class IPv4Base

Private _FirstOct As Byte
Private _SecOct As Byte
Private _ThirdOct As Byte
Private _FourthOct As Byte
Private _Class As String

' ++++++++++++++++++++++++++++++++++++++++++++++++++++
' Constructors
' ++++++++++++++++++++++++++++++++++++++++++++++++++++

Public Sub New()
_FirstOct = 0
.....
End Sub

' New() accepting Bytes
Public Sub New(ByVal byte1 As Byte, ByVal byte2 As Byte, ByVal byte3 As Byte, ByVal byte4 As Byte)
_FirstOct = byte1
.....
End Sub

' New() accepting Strings
' Requires validation
Public Sub New(ByVal str1 As String, ByVal str2 As String, ByVal str3 As String, ByVal str4 As String)
Dim bytesArray(3) As Byte
Dim index As Int16 = 0

' Validating Strings
Try
bytesArray(0) = CByte(str1)
...
Catch ex As Exception
MessageBox.Show("Error .....)
' Exit Sub New() if have errors
Exit Sub
End Try

' If validated then set values
_FirstOct = bytesArray(0)
_SecOct = bytesArray(1)
_ThirdOct = bytesArray(2)
_FourthOct = bytesArray(3)

End Sub

' ++++++++++++++++++++++++++++++++++++++++++++++++++++
' Properties
' ++++++++++++++++++++++++++++++++++++++++++++++++++++

Public Overridable Property FirstOct() As Byte
Get
Return _FirstOct
End Get
Set(ByVal value As Byte)
_FirstOct = value
End Set
End Property

Public Overridable Property SecOct() As Byte
Get
Return _SecOct
End Get
Set(ByVal value As Byte)
_SecOct = value
End Set
End Property

Public Overridable Property ThirdOct() As Byte
Get
Return _ThirdOct
End Get
Set(ByVal value As Byte)
_ThirdOct = value
End Set
End Property

Public Overridable Property FourthOct() As Byte
Get
Return _FourthOct
End Get
Set(ByVal value As Byte)
_FourthOct = value
End Set
End Property

Public Property IPClass() As String
Get
Return _Class
End Get
Set(ByVal value As String)
_Class = value
End Set
End Property

Public Class SubnetMask
Inherits IPv4Base

Private _SlashNotation As Integer
Private validValues() As Byte = {0, 128, 192, 224, 240, 248, 252}

Public Property SlashNotation() As Integer
Get
Return _SlashNotation
End Get
Set(ByVal value As Integer)
' Validating
......
Exit Property
End If
_SlashNotation = value

' Sync with Decimal notation

End Set
End Property

Public Sub New()

End Sub

' New() accepting Bytes
' My Sub New() are copied and pasted from IPv4Base is this supposed to be done,
' I thought they should be inherited?
Public Sub New(ByVal byte1 As Byte, ByVal byte2 As Byte, ByVal byte3 As Byte, ByVal byte4 As Byte)
FirstOct = byte1
.....
End Sub

' New() accepting Strings
' Requires validation
Public Sub New(ByVal str1 As String, ByVal str2 As String, ByVal str3 As String, ByVal str4 As String)
Dim bytesArray(3) As Byte
Dim index As Int16 = 0

' Validating Strings
Try
bytesArray(0) = CByte(str1)
bytesArray(1) = ......
Catch ex As Exception
MessageBox.Show("Error .....)
' Exit Sub New() if have errors
Exit Sub
End Try

' If validated then set values
FirstOct = bytesArray(0)
SecOct = bytesArray(1)
ThirdOct = bytesArray(2)
FourthOct = bytesArray(3)

End Sub

So basically i want to change the way set() is done in the SubnetMask class. I tried overidding:

Public Overrides Property FirstOct() As Byte
Get
Return _FirstOct
' error:IPv4Base._FirstOct is not accessible because its 'Private'
End Get
Set(ByVal value As Byte)
_FirstOct = value ' same Error Here also
End Set
End Property

IceAngel89 at 2007-9-4 >

Additionally, you don't need to copy the code in your sub new() functions if it's the same functionality. Just call the appropriate base function MyBase.New(...) (didn't we already do this in another thread?)

SJWhiteley at 2007-9-4 >

That's OK...

Public Class BaseClass

Sub New()

End Sub

Sub New(ByVal a As Integer, ByVal b As Integer)

' Lots of code here...

End Sub

End Class

Public Class InheritedClass : Inherits BaseClass

Sub New(ByVal a As Integer, ByVal b As Integer)

MyBase.New(a, b)

End Sub

End Class

As you can see in the inherited class, instead of duplicating all the code from the prameterized constructor in the base class, we simply call the base parameterized constructor. The reason is that the inherited class does not expose the base class parameterized constructor: we must expose it manually.

Hope that makes a bit more sense.

SJWhiteley at 2007-9-4 >