如何在VBA类中处理MSForms.TextBox的AfterUpdate等事件？

问题背景 #

通过WithEvents定义关联MSForms.TextBox的自定义类后，仅能处理Change事件，无法捕获AfterUpdate、BeforeUpdate、Enter和Exit事件。操作流程如下：

1. 用户窗体代码 #

Option Explicit

Private thisTextBox1 As Class1
Private thisTextBox2 As Class1

Private Sub CommandButton1_Click()
    Set thisTextBox1 = New Class1
    Set thisTextBox2 = New Class1
    thisTextBox1.Init TextBox1
    thisTextBox2.Init TextBox2
End Sub

Private Sub UserForm_Terminate()
    Set thisTextBox1 = Nothing
    Set thisTextBox2 = Nothing
End Sub

2. 初始自定义类代码（仅支持Change事件） #

'@Folder("VBAProject")
Option Explicit

Private WithEvents thisTextBox As MSForms.TextBox
Private thisTextBoxControl As MSForms.Control

Public Sub Init(ByVal MyTextBox As MSForms.TextBox)
    Set thisTextBox = MyTextBox
    Set thisTextBoxControl = MyTextBox.Parent.Controls.Item(MyTextBox.Name)
End Sub

Private Sub thisTextBox_Change()
    Debug.Print "thisTextBox_Change " & thisTextBox.Name & " " & thisTextBox.Text
End Sub

3. 错误尝试（触发“对象或类不支持事件集”） #

尝试将thisTextBoxControl改为WithEvents声明后，编译通过但赋值时出错：

Private WithEvents thisTextBox As MSForms.TextBox
Private WithEvents thisTextBoxControl As MSForms.Control

Public Sub Init(ByVal MyTextBox As MSForms.TextBox)
    Set thisTextBox = MyTextBox
    Set thisTextBoxControl = MyTextBox.Parent.Controls.Item(MyTextBox.Name)
End Sub

Private Sub thisTextBox_Change()
    Debug.Print "thisTextBox_Change " & thisTextBox.Name & " " & thisTextBox.Text
End Sub

Private Sub thisTextBoxControl_Enter()
    Debug.Print "thisTextBoxControl_Enter " & thisTextBoxControl.Name
End Sub

可行解决方案 #

无需额外声明通用控件类型的WithEvents变量，直接基于MSForms.TextBox的WithEvents变量添加所有需要的事件处理过程即可——MSForms.TextBox原生支持目标事件。

修改后的Class1代码：

'@Folder("VBAProject")
Option Explicit

Private WithEvents thisTextBox As MSForms.TextBox

Public Sub Init(ByVal MyTextBox As MSForms.TextBox)
    Set thisTextBox = MyTextBox
End Sub

Private Sub thisTextBox_Change()
    Debug.Print "thisTextBox_Change " & thisTextBox.Name & " " & thisTextBox.Text
End Sub

Private Sub thisTextBox_AfterUpdate()
    Debug.Print "thisTextBox_AfterUpdate " & thisTextBox.Name & " " & thisTextBox.Text
End Sub

Private Sub thisTextBox_BeforeUpdate(ByVal Cancel As MSForms.ReturnBoolean)
    Debug.Print "thisTextBox_BeforeUpdate " & thisTextBox.Name & " " & thisTextBox.Text
    ' 如需取消更新操作，可设置 Cancel = True
End Sub

Private Sub thisTextBox_Enter()
    Debug.Print "thisTextBox_Enter " & thisTextBox.Name
End Sub

Private Sub thisTextBox_Exit(ByVal Cancel As MSForms.ReturnBoolean)
    Debug.Print "thisTextBox_Exit " & thisTextBox.Name
    ' 如需取消退出操作，可设置 Cancel = True
End Sub

错误原因说明 #

MSForms.Control是通用控件基类，不包含TextBox特有的事件集合，因此用WithEvents声明该类型变量后，赋值时会触发“对象或类不支持事件集”的错误。而MSForms.TextBox是具体的控件类型，自带完整的原生事件，直接使用其WithEvents变量即可捕获所有目标事件。

内容的提问来源于stack exchange，提问作者Marek Fiołka