Object OnChange

[cday119]

Hey I have class and I was wondering if I can do an OnChange event with the class. Basically if someone tries closing the program without saving the object I went a warning to pop up. The OnChange event will switch a changed property in the class.

Thanks

[Plater]

If you have your own custom class, add a private boolean to determine if anything about the class has changed.
Then all all the function/properties of the class that would change it, be sure to set that boolean to true and trigger that onchange event?

[cday119]

If you have your own custom class, add a private boolean to determine if anything about the class has changed.
Then all all the function/properties of the class that would change it, be sure to set that boolean to true and trigger that onchange event?

I am trying this to handle the onchange event but it comes up with an error
for Me.OnChange - Event OnChange not found. How do I add an onchange event?

 Public Sub OnChange() Handles Me.OnChange
        ProfileChanged = True
    End Sub

And here is the entire Class code

Public Class Profile

    Private ProfileFileName As String
    Private ProfileDescription As String
    Private ProfileVersion As Integer
    Private ProfileNumAutoReduction As Integer
    Private ProfileNumberLines As Integer
    Private ProfilePrinterName As String
    Private ProfilePrintOrientation As String
    Private ProfilePaperSize As Integer
    Private ProfileColumnsPerPage As Integer
    Private ProfileRowsPerPage As Integer
    Private ProfileHorizontalDisplacement As Integer
    Private ProfileVerticalDisplacement As Integer
    Private ProfileHorizontalSeperation As Integer
    Private ProfileVerticalSeperation As Integer
    Private ProfileLines As New Collection
    Private ProfileChanged As Boolean = False


    Public Sub OnChange() Handles Me.OnChange
        ProfileChanged = True
    End Sub
    Public Sub New()
        'This sub sets the defaults of the default Profile.
        Me.Description = "New Profile"
        Me.Version = 2
        Me.NumAutoReduction = 4
        Me.NumberLines = 4
        Me.PrintOrientation = 2
        Me.PaperSize = 260
        Me.ColumnsPerPage = 1
        Me.RowsPerPage = 1
        Me.HorizontalDisplacement = 0
        Me.VerticalDisplacement = 0
        Me.HorizontalSeperation = 0
        Me.VerticalSeperation = 0
        Me.Changed = False

        Dim Line As Collection = New Collection
        Dim Line2 As Collection = New Collection
        Dim Line3 As Collection = New Collection
        Dim Line4 As Collection = New Collection
        Dim Reduction As Collection = New Collection
        Dim Reduction2 As Collection = New Collection
        Dim Reduction3 As Collection = New Collection
        Dim Reduction4 As Collection = New Collection
        Dim Reduction5 As Collection = New Collection

        Dim i As Integer = 1

        Reduction.Add("True", "Enabled")
        Reduction.Add("24", "Size")
        Reduction.Add("Arial", "Font")
        Reduction.Add("False", "Bold")
        Reduction.Add("False", "Caps")
        Reduction.Add("False", "Italic")
        Reduction.Add("610", "HorizontalDisplacement")
        Reduction.Add("-50", "VerticalDisplacement")
        Reduction.Add("3960", "Width")
        Reduction2.Add("18", "Size")
        Reduction2.Add("Arial", "Font")
        Reduction2.Add("False", "Bold")
        Reduction2.Add("False", "Caps")
        Reduction2.Add("False", "Italic")
        Reduction2.Add("610", "HorizontalDisplacement")
        Reduction2.Add("300", "VerticalDisplacement")
        Reduction2.Add("3960", "Width")
        Reduction3.Add("16", "Size")
        Reduction3.Add("Arial Narrow", "Font")
        Reduction3.Add("False", "Bold")
        Reduction3.Add("False", "Caps")
        Reduction3.Add("False", "Italic")
        Reduction3.Add("610", "HorizontalDisplacement")
        Reduction3.Add("500", "VerticalDisplacement")
        Reduction3.Add("3960", "Width")
        Reduction4.Add("14", "Size")
        Reduction4.Add("Arial Narrow", "Font")
        Reduction4.Add("610", "HorizontalDisplacement")
        Reduction4.Add("-50", "VerticalDisplacement")
        Reduction4.Add("3960", "Width")
        Reduction4.Add("False", "Bold")
        Reduction4.Add("False", "Caps")
        Reduction4.Add("False", "Italic")
        Reduction5.Add("12", "Size")
        Reduction5.Add("Arial Narrow", "Font")
        Reduction5.Add("False", "Bold")
        Reduction5.Add("False", "Caps")
        Reduction5.Add("False", "Italic")
        Reduction5.Add("610", "HorizontalDisplacement")
        Reduction5.Add("-50", "VerticalDisplacement")
        Reduction5.Add("3960", "Width")

        Line.Add(Reduction, "Reduction1")
        Line.Add(Reduction2, "Reduction2")
        Line.Add(Reduction3, "Reduction3")
        Line.Add(Reduction4, "Reduction4")
        Line2.Add(Reduction2, "Reduction1")
        Line2.Add(Reduction3, "Reduction2")
        Line2.Add(Reduction4, "Reduction3")
        Line2.Add(Reduction5, "Reduction4")
        Line3.Add(Reduction3, "Reduction1")
        Line3.Add(Reduction4, "Reduction2")
        Line3.Add(Reduction5, "Reduction3")
        Line3.Add(Reduction5, "Reduction4")
        Line4.Add(Reduction4, "Reduction1")
        Line4.Add(Reduction5, "Reduction2")
        Line4.Add(Reduction5, "Reduction3")
        Line4.Add(Reduction5, "Reduction4")

        Me.Lines.Add(Line, "Line1")
        Me.Lines.Add(Line2, "Line2")
        Me.Lines.Add(Line3, "Line3")
        Me.Lines.Add(Line4, "Line4")

    End Sub

    Property Description() As String
        Get
            Return ProfileDescription
        End Get
        Set(ByVal value As String)
            ProfileDescription = value
        End Set
    End Property

    Property FileName() As String
        Get
            Return ProfileFileName
        End Get
        Set(ByVal value As String)
            ProfileFileName = value
        End Set
    End Property

    Property Version() As Integer
        Get
            Return ProfileVersion
        End Get
        Set(ByVal value As Integer)
            ProfileVersion = value
        End Set
    End Property

    Property NumAutoReduction() As Integer
        Get
            Return ProfileNumAutoReduction
        End Get
        Set(ByVal value As Integer)
            ProfileNumAutoReduction = value
        End Set
    End Property

    Property PrinterName() As String
        Get
            Return ProfilePrinterName
        End Get
        Set(ByVal value As String)
            ProfilePrinterName = value
        End Set
    End Property

    Property PrintOrientation() As String
        Get
            Return ProfilePrintOrientation
        End Get
        Set(ByVal value As String)
            ProfilePrintOrientation = value
        End Set
    End Property

    Property PaperSize() As Integer
        Get
            Return ProfilePaperSize
        End Get
        Set(ByVal value As Integer)
            ProfilePaperSize = value
        End Set
    End Property

    Property ColumnsPerPage() As Integer
        Get
            Return ProfileColumnsPerPage
        End Get
        Set(ByVal value As Integer)
            ProfileColumnsPerPage = value
        End Set
    End Property

    Property RowsPerPage() As Integer
        Get
            Return ProfileRowsPerPage
        End Get
        Set(ByVal value As Integer)
            ProfileRowsPerPage = value
        End Set
    End Property

    Property HorizontalDisplacement() As Integer
        Get
            Return ProfileHorizontalDisplacement
        End Get
        Set(ByVal value As Integer)
            ProfileHorizontalDisplacement = value
        End Set
    End Property

    Property VerticalDisplacement() As Integer
        Get
            Return ProfileVerticalDisplacement
        End Get
        Set(ByVal value As Integer)
            ProfileVerticalDisplacement = value
        End Set
    End Property

    Property HorizontalSeperation() As Integer
        Get
            Return ProfileHorizontalSeperation
        End Get
        Set(ByVal value As Integer)
            ProfileHorizontalSeperation = value
        End Set
    End Property

    Property VerticalSeperation() As Integer
        Get
            Return ProfileVerticalSeperation
        End Get
        Set(ByVal value As Integer)
            ProfileVerticalSeperation = value
        End Set
    End Property

    Public Property Lines() As Collection
        Get
            Return ProfileLines
        End Get
        Set(ByVal value As Collection)
            ProfileLines = value
        End Set
    End Property

    Property NumberLines() As Integer
        Get
            Return ProfileNumberLines
        End Get
        Set(ByVal value As Integer)
            ProfileNumberLines = value
        End Set
    End Property

    Property Changed() As Boolean
        Get
            Return ProfileChanged
        End Get
        Set(ByVal value As Boolean)
            ProfileChanged = value
        End Set
    End Property

End Class

[Plater]

I think I have got something confused here.
I no longer understand why you want an event.
If at every function/property of your class that changes something, you ensure the boolean to be true. Then when you save, set the boolean to false. Simply checking that the boolean is false before closing would tell you if something has been changed?

[cday119]

I think I have got something confused here.
I no longer understand why you want an event.
If at every function/property of your class that changes something, you ensure the boolean to be true. Then when you save, set the boolean to false. Simply checking that the boolean is false before closing would tell you if something has been changed?

The thing is I don't want to write in every place I change the class that the class has chenged. This is why I want an onchange event. I just don't know how or if you can add an onchange event to a class.

[Plater]

If you want an onchange event, you would have to have to create it.
Which would entail coding it into every palce the object was changed.
OR have a background thread running that constantly compares the object to another instance of itself.
It might also be possible to do some unsafe code and watch the memory address to see if it has changed (Or possibly with serialization.. checking to see if the serializaed version is different)

This is where good solid design before creating your objects come in to play.

[cday119]

If you want an onchange event, you would have to have to create it.
Which would entail coding it into every palce the object was changed.
OR have a background thread running that constantly compares the object to another instance of itself.
It might also be possible to do some unsafe code and watch the memory address to see if it has changed (Or possibly with serialization.. checking to see if the serializaed version is different)

This is where good solid design before creating your objects come in to play.

So I can't do an onChange event like say a text box has a TextChanged event?
Where everytime a textbox changes text an event is triggered but you don't have to code an event everywhere you change a textbox's text.

[Plater]

So I can't do an onChange event like say a text box has a TextChanged event?
Where everytime a textbox changes text an event is triggered but you don't have to code an event everywhere you change a textbox's text.

Not unless you make it yourself.