asked on

link list of object class in VB6

I have 3 classes + 1 form: CListNode, CList, CCallCode, and a form to test

CCallCode
----------------------------------------------------------------------------------------------------------------
Private mCallCodeID As Integer
Private mCallCode As String

Public Property Get CallCodeID() As Integer
CallCodeID = mCallCodeID
End Property

Public Property Let CallCodeID(ByVal ID As Integer)
mCallCodeID = ID
End Property

Public Property Get CallCode() As String
CallCode = mCallCode
End Property

Public Property Let CallCode(ByVal Code As String)
mCallCode = Code
End Property

----------------------------------------------------------------------------------------------------------------

'CListNode'
----------------------------------------------------------------------------------------------------------------
Private mNodeData As Object
Private mNextNode As CListNode

Public Property Get Data() As Object
Data = mNodeData
End Property

Public Property Let Data(ByVal vNewValue As Object)
Set mNodeData = vNewValue
End Property

Public Property Get NextNode() As CListNode
Set NextNode = mNextNode
End Property

Public Property Let NextNode(ByVal vNewValue As Variant)
Set mNextNode = vNewValue
End Property
----------------------------------------------------------------------------------------------------------------

CList
----------------------------------------------------------------------------------------------------------------
Private mFirstNode As CListNode
Private mLastNode As CListNode

Public Function IsEmpty() As Boolean
IsEmpty = IIf(mFirstNode Is Nothing, True, False)
End Function

Public Sub InsertAtFront(insertItem As Variant)
Dim tempNode As CListNode

If IsEmpty() Then
Set mFirstNode = New CListNode
Set mLastNode = mFirstNode
Else
Set tempNode = mFirstNode
Set mFirstNode = New CListNode
mFirstNode.NextNode = tempNode
End If
mFirstNode.Data = insertItem
End Sub

Public Sub InsertAtBack(insertItem As Variant)
Dim tempNode As CListNode
If IsEmpty() Then
Set mLastNode = New CListNode
Set mFirstNode = mLastNode
Else
Set tempNode = mLastNode
Set mLastNode = New CListNode
tempNode.NextNode = mLastNode
End If
mLastNode.Data = insertItem
End Sub
----------------------------------------------------------------------------------------------------------------

A form
----------------------------------------------------------------------------------------------------------------
Private mCList As CList

Private Sub cmdCallCode_Click()

Dim mCallCode1 As New CCallCodes
Dim mCallCode2 As New CCallCodes

With mCallCode1
.CallCodeID = 1000
.CallCode = "Call Mom!"
End With

With mCallCode2
.CallCodeID = 1001
.CallCode = "Nurse Needed"
End With

Call mCList.InsertAtFront(mCallCode1)
Call mCList.InsertAtBack(mCallCode2)

End Sub
----------------------------------------------------------------------------------------------------------------

There is no error compiling, but now i don't know how to access mCallCodeID and mCallCode in each of the CallCode object in the link list...

ASKER CERTIFIED SOLUTION

EDDYKT

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SOLUTION

Mike Tomlinson

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TungVan

ASKER

Thanks for all your help...I decided to go with Collection since it is more easy....:)

Mike Tomlinson

TungVan,

Here is how to encapsulate the Collection object in a Class so that you can use it in a For...Next loop.

<<< IMPORTANT >>> Follow the instructions at the bottom of the class in the newEnum() function.

' ----------------------------------------------------------------------------
' Form1
' ----------------------------------------------------------------------------
Option Explicit

Private List As New CList

Private Sub Form_Load()
Dim mCallCode As CCallCode

Set mCallCode = New CCallCode
With mCallCode
.CallCodeID = 1000
.CallCode = "Call Mom!"
End With
List.InsertAtFront mCallCode

Set mCallCode = New CCallCode
With mCallCode
.CallCodeID = 1001
.CallCode = "Nurse Needed"
End With
List.InsertAtBack mCallCode
End Sub

Private Sub Command1_Click()
Dim mCallCode As CCallCode

For Each mCallCode In List ' <---- Enumerating the nodes in your CList with For...Next
Debug.Print mCallCode.CallCode
Debug.Print mCallCode.CallCodeID
Next
End Sub

' ----------------------------------------------------------------------------
' Class CList
' ----------------------------------------------------------------------------
Option Explicit

Private myCollection As New Collection

Public Sub Clear()
Set myCollection = New Collection
End Sub

Public Function Count() As Long
Count = myCollection.Count
End Function

Public Function IsEmpty() As Boolean
IsEmpty = (Me.Count = 0)
End Function

Public Sub InsertAtFront(ByRef insertItem As CCallCode)
If Me.Count = 0 Then
' can't add item before the first item if the collection is empty
myCollection.Add insertItem
Else
' insert item before the first item
myCollection.Add insertItem, , 1
End If
End Sub

Public Sub InsertAtBack(ByRef insertItem As CCallCode)
myCollection.Add insertItem
End Sub

Public Function newEnum() As IUnknown
On Error Resume Next
' Click on Tools --> Procedure Attributes --> Advanced
' This function should be a hidden member and the Procedure Id should be -4
Set newEnum = myCollection.[_NewEnum]
End Function