VBA Collection Class: Unwated Data Overwriting - vba

Question

I have a Collection Class (or rather a dictionary class, in this case) that is used to store a variable amount of edge objects. When I try to populate the Dictionary that holds all the information via loop, the data is continuously overwritten and I cannot seem to figure out why. The code for the class in question follows:
Option Explicit
Private pEdges As New Scripting.Dictionary
Property Get Count() As Long
Count = pEdges.Count
End Property
Property Get EdgeByName(ByVal iName As Variant) As cEdge
Set EdgeByName = pEdges(iName)
End Property
'Would it be better to pass all of the data to this add sub, and create
'the class objects here, rather than creating a temporary class object and
'just passing it along?
Sub Add(ByVal iEdge As cEdge)
Dim Edge As New cEdge
Set Edge = iEdge
pEdges.Add Edge.Name, Edge
End Sub
Sub Remove(ByVal iName As Variant)
pEdges.Remove (iName)
End Sub
Sub RemoveAll()
pEdges.RemoveAll
End Sub
Sub PrintNames()
Dim Key As Variant
For Each Key In pEdges
Debug.Print Key & " - " & pEdges(Key).Name & vbCrLf;
Next
Debug.Print vbdrlf;
End Sub
Sub that generates the Edges object follows:
Sub CalculateEdges(cCavities() As cCavity, dEdges As cEdges)
Dim i As Integer
For i = 1 To UBound(cCavities)
Dim TempEdge As cEdge
Set TempEdge = New cEdge
Dim AdjSize As Integer
AdjSize = cCavities(i).AdjacencySize
If AdjSize> MaxEdges Then MaxEdges = AdjSize
Dim j As Integer
For j = 1 To AdjSize
With TempEdge
'Edge Names are a combination of two node names
.Name = cCavities(i).Name & cCavities(i).Adjacency(j)
'Sets the start node (Object) for the edge
.SetNode cCavities(i), 0
'Sets the end node (Object) for the edge
.SetNode BackGround.NodeByName(cCavities, cCavities(i).Adjacency(j)), 1
'Used later in program
.Value = 0
End With
dEdges.Add TempEdge
dEdges.PrintNames
Next j
Next i
End Sub
The output of the dEdges.PrintNames sub is what I have been using for debugging this (since the Watches window doesn't show the item data of a dictionary).
As the loops go on it prints the Key and the Name Value of the edge object that the key corresponds to. If working correctly, these two strings should be identical. As it is though, every time I add a new edge object to the dictionary, it overwrites the objects for all the previously entered keys. I have the suspicion that this is related to the fact that I create a TempEdge Variable to pass to the Collection Class, but I am not sure.
Example of output:
C1C2 - C1C2
C1C2 - C1C3
C1C3 - C1C3
C1C2 - C1C4
C1C3 - C1C4
C1C4 - C1C4
ETC
This is just one single data point being tested, but let me assure you that all the variables inside the cEdge object are overwritten, not just the name string. It is simply the easiest to check since it is just a string.
As a side note, if there is a way to see the Object stored in the dictionary, similar to the "Watches" window, I would very much like to know how to do it. The entire reason I am even using the temp edge at this point is so I can keep track of what data is going into the dictionary at any given point in the loop.
Second side note, If I can get this working I will most likely switch the cCavities array to a similar collection class. It is not currently one because I cant seem to get them working right.

Answer 1

Moving the Set "TempEdge = New cEdge" into the loop will create a new instance and a new pointer location with every loop while maintaining your collections references to previous pointers.
Sub CalculateEdges(cCavities() As cCavity, dEdges As cEdges)
Dim i As Integer
For i = 1 To UBound(cCavities)
Dim TempEdge As cEdge
Dim AdjSize As Integer
AdjSize = cCavities(i).AdjacencySize
If AdjSize> MaxEdges Then MaxEdges = AdjSize
Dim j As Integer
For j = 1 To AdjSize
Set TempEdge = New cEdge
With TempEdge
'Edge Names are a combination of two node names
.Name = cCavities(i).Name & cCavities(i).Adjacency(j)
'Sets the start node (Object) for the edge
.SetNode cCavities(i), 0
'Sets the end node (Object) for the edge
.SetNode BackGround.NodeByName(cCavities, cCavities(i).Adjacency(j)), 1
'Used later in program
.Value = 0
End With
dEdges.Add TempEdge
dEdges.PrintNames
Next j
Next i
End Sub

Answer 2

I went ahead with the idea to pass along all the data to the add routine, and it seems to have solved the issue. I would still like to know why the method I was using did not work, though, so please feel free to comment or answer with regards to that.
The solution was to change the cEdges.Add Sub to accept all the individual parameters that were once passed to the temporary edge variable:
Sub Add(ByVal iName As String, iNode1 As cCavity, iNode2 As cCavity, iValue As Integer)
Dim Edge As New cEdge
With Edge
.Name = iName
.SetNode iNode1, 0
.SetNode iNode2, 1
.Value = iValue
End With
pEdges.Add Edge.Name, Edge
End Sub
This changes the populating loop to look like:
Sub CalculateEdges(cCavities() As cCavity, dEdges As cEdges)
Dim i As Integer
For i = 1 To UBound(cCavities)
Dim AdjSize As Integer
AdjSize = cCavities(i).AdjacencySize
If AdjSize > MaxEdges Then MaxEdges = AdjSize
Dim j As Integer
For j = 1 To AdjSize
dEdges.Add cCavities(i).Name & cCavities(i).Adjacency(j), cCavities(i), BackGround.NodeByName(cCavities, cCavities(i).Adjacency(j)), 0
dEdges.PrintNames
Next j
Next i
End Sub
This code, especially the .Add line, could be cleaned up. I will most likely do that, but this is fine for now.
EDIT: Upon further research and a bit more trial and error, I have discovered the reason for the data being overwritten. The Set keyword only creates a pointer to the original value, effectively making my above code have one object, the TempEdge variable, and a whole bunch of different heads that pointed to it. That is why when the Temp edge was edited, all the subsequent heads changes.