If you want it to be "generalized", then you should design the implementation on an interface, not a class.
Use events in the child forms to notify the parent.
Use properties in the child forms for the parent to notify children.
Public Delegate Sub MessageDelegate(ByVal sender As Object, ByVal e As MessageEventArgs)
Public Class MessageEventArgs : Inherits EventArgs
Public Message As String
Public Sub New(ByVal msg As String)
Me.Message = msg
End Sub
End Class
Public Interface IController
Event ControllerEvent As MessageDelegate
Sub FireControllerEvent(ByVal msg As String)
End Interface
Public Class Controller : Implements IController
Public Event ControllerEvent As MessageDelegate Implements IController.ControllerEvent
Public Sub FireControllerEvent(ByVal msg As String) Implements IController.FireControllerEvent
Me.OnControllerEvent(New MessageEventArgs(msg))
End Sub
Protected Overridable Sub OnControllerEvent(ByVal e As MessageEventArgs)
RaiseEvent ControllerEvent(Me, e)
End Sub
End Class
'*************************************************************************'
Public Class Form1 'this class is the master form
Private msgController As IController
Private msgValue As Integer = 0
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Me.msgController = New Controller()
AddHandler msgController.ControllerEvent, AddressOf msgController_ControllerEvent
Dim childForm As New Form2(Me.msgController)
childForm.Show()
End Sub
Private Sub msgController_ControllerEvent(ByVal sender As Object, ByVal e As MessageEventArgs)
Me.msgValue += 1
Me.Text = e.Message & " " & Me.msgValue
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.msgController.FireControllerEvent("Form1 fired the event. ")
End Sub
Private Sub Me_FormClosing(ByVal sender As Object, ByVal e As FormClosingEventArgs) Handles Me.FormClosing
RemoveHandler msgController.ControllerEvent, AddressOf msgController_ControllerEvent
End Sub
End Class
'*************************************************************************'
Public Class Form2 'this class is the child form
Private msgController As IController
Private msgValue As Integer = 0
Public Sub New()
' This call is required by the Windows Form Designer.
InitializeComponent()
' Add any initialization after the InitializeComponent() call.
End Sub
Public Sub New(ByVal controller As IController)
Me.New()
Me.msgController = controller
End Sub
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Me.msgController.FireControllerEvent("Form2 fired the event. ")
End Sub
Private Sub Form2_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
AddHandler msgController.ControllerEvent, AddressOf msgController_ControllerEvent
End Sub
Private Sub msgController_ControllerEvent(ByVal sender As Object, ByVal e As MessageEventArgs)
Me.msgValue += 1
Me.Text = e.Message & " " & Me.msgValue.ToString()
End Sub
Private Sub Me_FormClosing(ByVal sender As Object, ByVal e As FormClosingEventArgs) Handles Me.FormClosing
RemoveHandler msgController.ControllerEvent, AddressOf msgController_ControllerEvent
End Sub
End Class
'*************************************************************************'
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