在VBA中使用父属性和数组时遇到错误

我得到VBA中的运行时错误91（对象variables或With块未设置）。

我正在尝试访问我构build的父类的属性，但我得到了错误91.我可以访问属性而不使用父属性，但是当我使用父属性时，我得到一个错误。

我有4个class（员工，员工，工程师和工程师）。 员工和工程师分别拥有一个员工和工程师的集合（我没有在这里使用集合对象，我只是使用一个简单的数组）。

我的员工类。

Option Explicit Private objEngineers As Engineers Private objEngineer As Engineer Private varCode As Variant Private Sub Class_Initialize() Set objEngineer = New Engineer Set objEngineer.Parent = Me End Sub Public Property Get Engineers() As Engineers Set Engineers = objEngineers End Property Public Property Set Engineers(objmEngineers As Engineers) Set objEngineers = objmEngineers End Property Public Property Get Code() As Variant Code = varCode End Property Public Property Let Code(varmCode As Variant) varCode = varmCode End Property 

员工类

 Option Explicit Private objEmployee() As Employee Sub Add() Dim i As Integer Dim objEngineers As Engineers Set objEngineers = New Engineers objEngineers.Add ReDim objEmployee(1 To 3) For i = 1 To 3 Set objEmployee(i) = New Employee objEmployee(i).Code = "Employee " & i Set objEmployee(i).Engineers = objEngineers Next End Sub Property Get Item(i As Integer) As Employee Set Item = objEmployee(i) End Property 

工程师class

  Option Explicit Private objEmployee As Employee Private varID As Variant Property Get Parent() As Employee Set Parent = objEmployee End Property Property Set Parent(objmEmployee As Employee) Set objEmployee = objmEmployee End Property Public Property Get ID() As Variant ID = varID End Property Public Property Let ID(varmID As Variant) varID = varmID End Property 

工程师class

  Option Explicit Private objEngineer() As Engineer Private objEmployee As Employee Sub Add() Dim i As Integer ReDim objEngineer(1 To 3) For i = 1 To 3 Set objEngineer(i) = New Engineer objEngineer(i).ID = "Engineer " & i Next End Sub Property Get Item(i As Integer) As Engineer Set Item = objEngineer(i) End Property 

最后是我的testing模块

  Option Explicit Sub Main() Dim objEmployees As Employees Dim i As Integer Set objEmployees = New Employees objEmployees.Add For i = 1 To 3 Debug.Print objEmployees.Item(i).Engineers.Item(i).ID Debug.Print objEmployees.Item(i).Code Debug.Print objEmployees.Item(i).Engineers.Item(i).Parent.Code Next End Sub 

我可以使循环中的第一行工作“工程师1”。 此外，给出“员工1”的第二行工作，但第三行应该给我与第二行相同的结果，我得到的错误。 当我使用工程师的Parent属性时，我无法访问Employee的属性。

我知道我错过了一些明显的东西，我找不到它。

Answer 1

基于迪克Kusleika 这个答案

蒸馏到足以certificate一个父母的财产

类模块ParentClass

 Option Explicit Private pName As String Private pChild As ChildClass Public Property Let Name(NewName As String) pName = NewName End Property Public Property Get Name() As String Name = pName End Property Public Property Get Child() As ChildClass Set Child = pChild End Property Public Sub Add(NewName As String) Set pChild = New ChildClass pChild.Name = NewName Set pChild.Parent = Me End Sub 

类模块ChildClass

 Option Explicit Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _ (dest As Any, Source As Any, ByVal bytes As Long) Private pName As String Private pParentPtr As Long Public Property Let Name(NewName As String) pName = NewName End Property Public Property Get Name() As String Name = pName End Property Public Property Get Parent() As ParentClass Set Parent = ObjFromPtr(pParentPtr) End Property Friend Property Set Parent(Obj As ParentClass) pParentPtr = ObjPtr(Obj) End Property Private Function ObjFromPtr(ByVal pObj As Long) As Object Dim Obj As Object CopyMemory Obj, pObj, 4 Set ObjFromPtr = Obj ' manually destroy the temporary object variable ' (if you omit this step you'll get a GPF!) CopyMemory Obj, 0&, 4 End Function 

用于演示目的的标准模块

 Sub Demo() Dim EgParent As ParentClass Dim EgChild As ChildClass Set EgParent = New ParentClass EgParent.Name = "I am the Parent" EgParent.Add "I am the Child" Set EgChild = EgParent.Child Debug.Print EgParent.Name Debug.Print EgChild.Name Debug.Print EgChild.Parent.Name End Sub