VBA：WithEvents难题 [英] VBA: WithEvents puzzle

问题描述

我有一个UserForm， xForm ，正在一个类模块中被实例化（让我们说 TestClass ）为：

I have a UserForm, xForm, that is being instantiated in a class module (let's say TestClass) as:

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

在xForm本身的类模块中，我有一些必须在表单关闭时执行的代码，只有当表单实际关闭时： / p>

At the class module of the xForm itself I have some code that must be executed on Form Closing, ONLY if the form actually closes:

'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，可以避免关闭窗体：

The QueryClose event is also treated in TestClass, and could avoid the form from closing:

'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

如何在xForm类模块中测试Cancel = True，在TestClass中设置？
让我们重新表述：如果TestClass中的Cancel被设置为True，我不能在xForm类模块中执行清除代码。如何才能实现？

How can I test for Cancel = True, set in TestClass, in the xForm class module? Let's rephrase it: If Cancel is set to True in TestClass, I must not do the cleanup code in the xForm class module. How can I accomplish that?

到目前为止，我已经考虑在xForm类（My_QueryClose？）中实现另一个事件，并将其提交到QueryClose事件。在代码后面我将只处理My_QueryClose事件，所以完全控制发生了什么。这是一个可行/更好的方法吗？

Until now, I have thought off of implementing another event in the xForm class (My_QueryClose?) and raise it on the QueryClose event. Outside the Code Behind Form I would deal only with the My_QueryClose event, so taking full control over what is happening. Is this a viable/better approach?

推荐答案

解决另一个事件的工作

代码不如我所期望的那样，尽管它不像我希望的那样整齐。

The code bellow do what I was expecting, although it is not as neat as I wish it could be.

在 UserForm1 代码：

'***** 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： p>

In the Class1 code:

'***** 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，测试Class：

In a basic module, to test the Class:

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

这是最终结果（调试窗口）：

And here's the end result (debug window):

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

这篇关于VBA：WithEvents难题的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！