Btukfyl

I'm using the base class Button in VB.net (VS2017) to create a new class called CDeviceButton. The CDeviceButton then forms as a base for other classes such as CMotorButton, CValveButton.

I want to set the Tag property in the child class CMotorButton but access it in the constructor in CDeviceButton. Doesn't work for me. It turns up being empty.

The Tag is set in the standard property when inserting the CMotorButtom instance into a form.

I've also tried to ensure teh the parent classes' constructors are run by setting mybase.New() as the first action in each constructor but that didn't change anything.

Any ideas for improvements?

Public Class CDeviceButton

    Inherits Button

    Public MMIControl As String = "MMIC"



    Public Sub New()

        MMIControl = "MMIC" & Tag

    End Sub

End class



Public Class CMotorButton

    Inherits CDeviceButton



    Sub New()

        'Do Something

    end Sub

End Class

When you try to concatenate Tag with a string, you are trying to add an object that is probably nothing. I set the Tag property first and used .ToString and it seems to work.

Public Class MyButton

        Inherits Button

        Public Property MyCustomTag As String

        Public Sub New()

            'Using an existing Property of Button

            Tag = "My Message"

            'Using a property you have added to the class

            MyCustomTag = "Message from MyCustomTag property : " & Tag.ToString

        End Sub

    End Class



    Public Class MyInheritedButton

        Inherits MyButton

        Public Sub New()

            If CStr(Tag) = "My Message" Then

                Debug.Print("Accessed Tag property from MyInheritedButton")

                Debug.Print(MyCustomTag)

            End If

        End Sub

    End Class

And then in the Form

Private Sub Test()

    Dim aButton As New MyInheritedButton

    MessageBox.Show(aButton.Tag.ToString)

    MessageBox.Show(aButton.MyCustomTag)

End Sub

Below is my solution I came up with that works. Basically I make sure that all initialization has taken place before reading the Tag property. What I experienced is that the Tag property is empty until the New() in CMotorButton has completed, even though the Tag property has been set when creating the instance of CMotorButton in the Form. TimerInitate has a Tick Time of 500 ms.

Not the most professional solution but works for what I need at the moment.

Another option could be multi threading but that I haven't tried and leave that for future tryouts.

Public Class CDeviceButton

    Inherits Button

    Public MMIControl As String = "MMIC"



    Public Sub New()

        TimerInitiate = New Timer(Me)

    End Sub

    Private Sub TimerInitiate_Tick(sender As Object, e As EventArgs) Handles TimerInitiate.Tick

        If Tag <> Nothing Then

            TimerInitiate.Stop()

            MMIControl = "MMIC" & Tag

        End If 

    End Sub

End class



Public Class CMotorButton

    Inherits CDeviceButton



    Sub New()

        'Do Some stuff

        TimerInitiate.Start()

    End Sub

    Private Sub CMotorButton_Click(sender As Object, e As EventArgs) Handles Me.Click

End Class