IEditableObject Interface

Adding some comments to the source would be helpful.  For example  inTxn  is probably used to say that the customer record is in a transaction and so should not be edited; but that's only apparent from reading through the code.   $0$0 $0I'm also unclear on whether that variable prevents updates, or if it just prevents their persistence (i.e. if an object receives two updates in quick succession, the first takes the isTxn "lock"; does the second fail, or is it somehow queued & completed later?  If it fails, what would a user see - there's no exceptions being thrown, so are they alerted, or does the system just ignore the second request?$0 $0

Imports System.ComponentModel
Imports Publisher
Public Class EditController
    Implements INotifyPropertyChanged
    Private _author As BL.Author
    Public Property Author() As BL.Author
        Get
            Return _author
        End Get
        Set(ByVal value As BL.Author)
            _author = value
            _author.BeginEdit()
            OnPropertyChanged("Author")
        End Set
    End Property
    Public Sub save()
        Author.EndEdit()
        'database update
        'BL.Author.save(_author)
    End Sub
    Public Sub cancel()
        Author.CancelEdit()
    End Sub
    Protected Overridable Sub OnPropertyChanged(ByVal propertyname As String)
        RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyname))
    End Sub
    Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
End Class


Imports System.ComponentModel
Public Class Author
Implements INotifyPropertyChanged
Implements IEditableObject
Private _firstname As String
Public Property Firstname() As String
Get
Return _firstname
End Get
Set(ByVal value As String)
_firstname = value
OnPropertyChanged("Firstname")
End Set
End Property
　
Private _lastname As String
Public Property Lastname() As String
Get
Return _lastname
End Get
Set(ByVal value As String)
_lastname = value
OnPropertyChanged("Lastname")
End Set
End Property
Public Sub New(ByVal fname As String, ByVal lname As String)
_firstname = fname
_lastname = lname
End Sub
　
Private _auID As String
Public Property auID() As String
Get
Return _auID
End Get
Set(ByVal value As String)
_auID = value
End Set
End Property
Protected Overridable Sub OnPropertyChanged(ByVal propertyname As String)
If _raisePropertyChanged Then
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(propertyname))
End If
End Sub
Public Event PropertyChanged(ByVal sender As Object, ByVal e As System.ComponentModel.PropertyChangedEventArgs) Implements System.ComponentModel.INotifyPropertyChanged.PropertyChanged
Private _raisePropertyChanged As Boolean = True
Private _oldFirstname As String
Private _oldLastname As String
Private _oldAddress As String
Private _oldState As String
Private _oldZip As String
Private _oldPhone As String
Private _oldContract As String
　
Public Sub BeginEdit() Implements System.ComponentModel.IEditableObject.BeginEdit
If _raisePropertyChanged Then
_raisePropertyChanged = False
_oldFirstname = Firstname
_oldLastname = Lastname
End If
End Sub
Public Sub CancelEdit() Implements System.ComponentModel.IEditableObject.CancelEdit
If _raisePropertyChanged.Equals(False) Then
_firstname = _oldFirstname
_lastname = _oldLastname
End If
End Sub
Public Sub EndEdit() Implements System.ComponentModel.IEditableObject.EndEdit
If Not _raisePropertyChanged Then
_raisePropertyChanged = True
_oldAddress = Nothing
_oldContract = Nothing
_oldFirstname = Nothing
_oldLastname = Nothing
_oldPhone = Nothing
_oldState = Nothing
_oldZip = Nothing
OnPropertyChanged("Firstname")
OnPropertyChanged("Lastname")
End If
End Sub
End Class

I am not entirely sure what the whole parent thing is doing nor the collection that they use.  I was able to get a simple class operational.  Might not be a bad idea to change the verbage on the two private declarations of the structure from custData to workingCopy and backupData to backupCopy or something.  Not a big deal, but it helps not to see the cust prefix keyword when you are learning this stuff.