Copying an instance of a class
S Figueroa
However, I will need two instances of this class, one that will store the
final information and other to keep the temporary changes. What I want to
do is to assign (copying) the properties of the final instance to the
temporary instance without having to write each property, using an
instruction such as:
Set TempInstance = FinalInstance
Also, I want to be able to change the temporary instance without affecting
the final instance with the changes. The final instance should be modified
only when the end-user presses the save button to confirm the change.
Thank you
Jeff Johnson
"S Figueroa" <sfig...@informedika.com> wrote in message
news:eXUrwW#5BHA.2156@tkmsftngp05...
> What I want to
> do is to assign (copying) the properties of the final instance to the
> temporary instance without having to write each property,
This has been asked several times before. The answer: sorry, not gonna
happen. You MUST copy the properties individually.
Search the newsgroup for keywords like "copy class object" for some broader
explanations and examples.
Larry Serflaten
> do is to assign (copying) the properties of the final instance to the
> temporary instance without having to write each property, using an
> instruction such as:
>
> the final instance with the changes. The final instance should be modified
> only when the end-user presses the save button to confirm the change.
>
> Thank you
>
>
You can see if this will fit your needs. For the demo, add a button to Form1
and add a Class to the project using default names.
' [ Form1 code ]
Option Explicit
Private objA As Class1
Private Sub Form_Load()
' Build object with data
Set objA = New Class1
objA.Name = "Data Object"
objA.Age = 10
objA.Data(7) = 1
End Sub
Private Sub Command1_Click()
Dim objB As New Class1
Cls
' Copy object to local variable
objB.Copy = objA.Copy
' Change local copy
objB.Name = "New Object"
objB.Age = 20
objB.Data(7) = 255
Print "COPIES:"
Display objA, objB
' Save changes
objA.Copy = objB.Copy
Print "CHANGED:"
Display objA, objB
End Sub
Private Sub Display(A As Class1, B As Class1)
' Display both
Print A.Name
Print A.Age
Print A.Data(7)
Print
Print B.Name
Print B.Age
Print B.Data(7)
Print: Print
End Sub
' [ Class1 code ]
Option Explicit
Private Type Settings
Name As String * 20
Age As Long
City As String * 20
State As String * 20
Bytes(0 To 7) As Byte
End Type
Private Type CopyData
Data As String * 68
End Type
Private My As Settings
Public Property Get Name() As String
Name = My.Name
End Property
Public Property Let Name(ByVal Value As String)
My.Name = Value
End Property
Public Property Get Age() As Long
Age = My.Age
End Property
Public Property Let Age(ByVal Value As Long)
My.Age = Value
End Property
Public Property Get Data(ByVal Index As Long) As Byte
Data = My.Bytes(Index)
End Property
Public Property Let Data(ByVal Index As Long, Value As Byte)
My.Bytes(Index) = Value
End Property
' Add Public properties as needed
Public Property Get Copy() As String
Dim Copier As CopyData
LSet Copier = My
Copy = Copier.Data
End Property
Public Property Let Copy(ByRef Data As String)
Dim Copier As CopyData
Copier.Data = Data
LSet My = Copier
End Property
For primative types it works OK....
LFS
What is the KB?: http://support.microsoft.com/default.aspx?ln=EN-US&pr=kbinfo&
RTFM? http://msdn.microsoft.com/library/devprods/vs6/vbasic/vbcon98/vbstartpage.htm
Where's the archive?: http://groups.google.com/advanced_group_search?q=group:microsoft.public.vb.*&hl=en&safe=off&num=50
Bob O`Bob
>
> What I want to
> do is to assign (copying) the properties of the final instance to the
> temporary instance without having to write each property, using an
> instruction such as:
>
> Set TempInstance = FinalInstance
There actually is (sort of) a way to do this.
But you'd still have to rewrite the class.
If all of the class' local storage is kept in elements
of an instance of a UDT, then you can expose the UDT
through property procedures.
Bob
--
posting from work, but representing only myself