Nested class & readonly properties - vb.net

Question

Outside the class I'd like to be able to access CCTV.Camera.Brightness property as ReadOnly, but methods within the CCTV class should be able to modify the Brightness property. Please can you advise on how to achieve this?
I think I need to add an Interface that exposes some properties and hides others, but I'm not sure of the implementation. [Note the constructor and main sub are obviously contrived for this example and testing].
Public Class CCTV
Public Class Camera
Public Property Name as String
Public Property Brightness as Integer
End Class
Dim cameras as New Dictionary(Of String, Camera)
Public Sub New()
Dim cam As New Camera
cam.Name = "driveway"
cam.Brightness = 5
cameras.Add(cam.Name, cam)
End Sub
Public Sub ChangeBrightness(value as Integer)
cameras("driveway").Brightness = value
End Sub
End Class
Sub main()
Dim MyCCTV = new CCTV
MyCCTV.ChangeBrightness(10)
if MyCCTV("driveway").Brightness = 10 then Console.Write("Brightness is 10")
End Sub

Answer 1

Get getter and the setter of a property can have different accessibility modifiers. In this case you want Brightness to be readable by everybody but only the code you trust should be able to write it. You do so like this:
Public Class Camera
Private _brightness As Integer
Public Property Brightness As Integer
Get
Return _brightness
End Get
Friend Set(value As Integer)
_brightness = Value
End Set
End Property
'' etc...
End Class
Note the added Friend keyword, it limits access to the code in the same project that Camera class is a part of. It can also be Private or Protected if you want to limit access to only code inside the Camera class or its derived classes.

Answer 2

no interface is need in this case.You simply have to create your property as readonly.when you set the property as readonly assume that the value will stored within a private variable and at that point should be better pass it or to a method or to the subnew using overloads methods let me show you an example:
Public Class CCTV
Public Class Camera
Private _Name As String
Public Property Name() As String
Get
Return _Name
End Get
Set(ByVal value As String)
_Name = value
End Set
End Property
Private _Brightness As String
Public ReadOnly Property Brightness() As String
Get
Return _Brightness
End Get
End Property
''' <summary>
''' Defautl sub new method
''' </summary>
''' <remarks></remarks>
Sub New()
End Sub
''' <summary>
''' second overload
''' </summary>
''' <param name="cameraName"></param>
''' <param name="brightness"></param>
''' <remarks></remarks>
Sub New(ByVal cameraName As String, ByVal brightness As Integer)
Me.Name = cameraName
Me._Brightness = brightness
End Sub
''' <summary>
''' Change brigthness
''' </summary>
''' <param name="value"></param>
''' <remarks></remarks>
Public Sub setUpCameraBrightness(ByVal value As Integer)
'take care to use private varibale so it will reflcet changes into propetry readonly
Me._Brightness = value
End Sub
End Class
Dim cameras As New Dictionary(Of String, Camera)
Public Sub New()
'two differnet approach
'first overaload:
Dim cam As New Camera()
cam.Name = "yourcamname"
cam.setUpCameraBrightness(10)
cameras.Add(cam.Name, cam)
''second approch declarative value:
Dim cam2 As New Camera("yourcamname", 10)
cameras.Add(cam2.Name, cam2)
End Sub
Public Sub ChangeBrightness(value As Integer)
cameras("driveway").setUpCameraBrightness(100)
End Sub
End Class
Sub main()
Dim MyCCTV = New CCTV
MyCCTV.ChangeBrightness(10)
If MyCCTV("driveway").Brightness = 10 Then Console.Write("Brightness is 10")
End Sub