VBA：WithEvents谜题

我有一个用户窗体， xForm ，是在一个类模块（假设TestClass ）实例化为：

'TestClass Dim Form as New xForm Private WithEvents EvForm as MSForms.UserForm Set EvForm = Form 

在xForm本身的类模块中，我有一些必须在Form Closing上执行的代码，只有当窗体实际closures时：

 'xForm class module Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer) 'Do some cleanup, otherwise the app would hang 'If not closing, don't cleanup anything, otherwise the app would hang End Sub 

QueryClose事件也在TestClass中处理，并可以避免窗体closures：

 'TestClass Private Sub EvForm_QueryClose(Cancel As Integer, CloseMode As Integer) 'Verify if closing is allowed based on User Control values Cancel = Not ClosingIsAllowed '<-- Pseudocode on the right side of "=" End Sub 

我该如何testingCancel = True，在TestFlass中的xForm类模块中设置？ 我们来重述一下：如果在TestClass中将Cancel设置为True，我不能在xForm类模块中执行清理代码。 我怎么能做到这一点？

到现在为止，我已经考虑过在xForm类（My_QueryClose？）中实现另一个事件，并在QueryClose事件中引发它。 在表单后面的代码之外我只会处理My_QueryClose事件，所以要完全控制发生的事情。 这是一个可行的/更好的方法？

Answer 1

不能让你的定制事件的想法成为正面或反面，但是让一个class级与另一个class级（forms或其他任何东西，无所谓）交谈的方式就是联系起来; 这里是一个干净的例子：

基本TestClass持有表单对象（这里没有需要的事件，让表单处理）

 'TestClass code Private MyForm As UserForm Private mbleCanClose As Boolean Public Property Get CanClose() As Boolean CanClose = mbleCanClose End Property Public Property Let CanClose(pbleCanClose As Boolean) mbleCanClose = pbleCanClose End Property Public Property Get MyFormProp() As UserForm1 Set MyFormProp = MyForm End Property 

将自定义对象和属性添加到窗体本身

 'UserForm1 code Private mParent As TestClass Public Property Get Parent() As TestClass Set Parent = mParent End Property Public Property Set Parent(pParent As TestClass) Set mParent = pParent End Property 

调用TestClass创build窗体如下所示：

 'TestClass code Private Sub Class_Initialize() Set MyForm = New UserForm1 Load MyForm Set MyForm.Parent = Me End Sub 

然后，当要closures表单时，请检查您是否可以：

 'UserForm1 code Public Function WillMyParentLetMeClose() As Boolean If Not (mParent Is Nothing) Then WillMyParentLetMeClose = mParent.CanClose End If End Function Private Sub CommandButton1_Click() If WillMyParentLetMeClose = True Then Unload Me End If End Sub 

这是它想要调用的

 'standard module code Public Sub Test_TestClass() Dim myclass As TestClass Set myclass = New TestClass myclass.MyFormProp.Show End Sub 

Answer 2

一个解决方法宣布另一个事件

下面的代码按照我期望的那样做，尽pipe它不像我希望的那样整齐。

在UserForm1代码中：

 '***** UserForm1 Public Event MyQueryClose(ByRef Cancel As Integer, ByRef CloseMode As Integer, ByRef Status As String) Private Sub UserForm_QueryClose(Cancel As Integer, CloseMode As Integer) Dim Status As String Cancel = True Status = "QueryClose" Debug.Print "Entered QueryClose" Debug.Print "Cancel = " & Cancel Debug.Print "Status = " & Status Debug.Print "Just before raising MyQueryClose" RaiseEvent MyQueryClose(Cancel, CloseMode, Status) Debug.Print "Just got back from MyQueryClose" Debug.Print "Cancel = " & Cancel Debug.Print "Status = " & Status End Sub 

在Class1代码中：

 '***** Class1 Dim UserForm As New UserForm1 Private WithEvents UF As UserForm1 Sub DoIt() Set UF = UserForm UserForm.Show End Sub Private Sub UF_MyQueryClose(Cancel As Integer, CloseMode As Integer, Status As String) Debug.Print "Just entered MyQueryClose" Cancel = False Status = "MY QueryClose" End Sub 

在基本模块中 ，要testingClass：

 '***** Basic module Sub TestClass() Dim C As New Class1 C.DoIt End Sub 

这里是最终结果（debugging窗口）：

 TestClass Entered QueryClose Cancel = -1 Status = QueryClose Just before raising MyQueryClose Just entered MyQueryClose Just got back from MyQueryClose Cancel = 0 Status = MY QueryClose