Interfaces & Sub-classes with different types - vb.net

Question

I have the following situation, that I'm pretty sure can be solved through the use of interfaces, but am not quite experienced enough to implement and keep losing myself.
Public Class IPGateway
Property Hostname As String
Property Port As Integer
Public Function Read()
Return OtherClass.Read(Hostname, Port)
End Sub
End Class
Public Class SerialGateway
Property Port As String
Property Baud As Integer
Public Sub Read()
Return YetAnotherClass.Read(Port, Baud)
End Sub
End Class
Public Sub Main()
Dim GatewayList as New List(of Gateways?) <- Interface here?
GatewayList.Add(SerialGateway)
GatewayList.Add(IPGateway)
For each gateway in GatewayList
Console.Write(gateway.Hostname() OR gateway.Baud)
Console.Write(gateway.Read())
Next
End Sub
I would welcome advice on how to best implement this approach?

Answer 1

You have 2 choises, one with Abstract Classes (MustInherit for VB) and one with interfaces. You have to decide which one works best for you!
Module Module1
Sub Main()
Console.WriteLine("With Abstract Classes")
Dim GatewayList As New List(Of TheBase)
GatewayList.Add(New SerialGateway With {.Baud = 5, .Port = "10"})
GatewayList.Add(New IPGateway With {.Hostname = "Test", .Port = "15"})
For Each gateway In GatewayList
Console.WriteLine(gateway.Port)
If TypeOf gateway Is SerialGateway Then
Console.WriteLine(DirectCast(gateway, SerialGateway).Baud)
ElseIf TypeOf gateway Is IPGateway Then
Console.WriteLine(DirectCast(gateway, IPGateway).Hostname)
End If
Console.WriteLine(gateway.Read())
Next
Console.WriteLine("With Interface")
Dim GatewayList2 As New List(Of TestIn)
GatewayList2.Add(New SerialGateway2 With {.Baud = "5", .Port = "10"})
GatewayList2.Add(New IPGateway2 With {.Hostname = "Test", .Port = "15"})
For Each gateway As TestIn In GatewayList2
Console.WriteLine(gateway.Port)
Console.WriteLine(gateway.Property2)
Console.WriteLine(gateway.Read())
Next
Console.ReadLine()
End Sub
End Module
Public Class IPGateway
Inherits TheBase
Property Hostname As String
Public Overrides Function Read() As String
Return "IPGateway"
End Function
End Class
Public Class SerialGateway
Inherits TheBase
Property Baud As Integer
Public Overrides Function Read() As String
Return "SerialGateway"
End Function
End Class
Public MustInherit Class TheBase
Public Property Port As String
Public MustOverride Function Read() As String
End Class
Public Interface TestIn
Property Port As String
Property Property2 As String
Function Read() As String
End Interface
Public Class SerialGateway2
Implements TestIn
Public Property Port As String Implements TestIn.Port
Public Property Baud As String Implements TestIn.Property2
Public Function Read() As String Implements TestIn.Read
Return "SerialGateway2"
End Function
End Class
Public Class IPGateway2
Implements TestIn
Public Property Port As String Implements TestIn.Port
Public Property Hostname As String Implements TestIn.Property2
Public Function Read() As String Implements TestIn.Read
Return "IPGateway2"
End Function
End Class