在向用户窗体添加控件时,以下内容有何区别。我不确定在何时使用特定的控件是适当的。
Dim aButton1 as MSFORMS.CommandButton
Dim aButton2 as Control.CommandButton
Dim aButton3 as CommandButton
首先添加UserForm。然后在VBA IDE中按F2,将会出现对象浏览器。在左上角是一个组合框,选择MSForms。在类列表中,您可以看到属于MSForms对象库的类。
您可以在该列表中看到CommandButton和Control:
在代码中声明CommandButton类型的变量:
Dim button1 As MSForms.CommandButton
Dim button2 As CommandButton
变量button1肯定是来自MSForms的CommandButton类型。而button2可能是你在本地VBA项目中定义的自己的类,但是如果你的本地VBA项目中没有包含这样的类,它也会被认为是来自MSForms。然而,如果你引用另一个对象库,比如'MSFoo',其中也包含CommandButton类,你就必须像这样完全限定声明它们:
Dim button1 As MSForms.CommandButton
Dim button2 As MSFoo.CommandButton
在您的代码中声明一个 Control 类型的变量:
Dim controlObject As MSForms.Control
使用 Control 类型的变量作为控件的基类。例如,枚举 Controls 集合:
For Each controlObject In Me.Controls
Debug.Print VBA.TypeName(controlObject)
Next controlObject
Private Sub PrinControlName(ByRef c As MSForms.Control)
Debug.Print c.Name
End Sub
因此,我认为在大多数情况下使用完全限定名(如MSForms.CommandButton)是适当的。 使用Control.CommandButton是错误的,并且在您引用了一个名为“Control”的对象库并带有其中的Class CommandButton之前无法编译。
编辑:
这里有一个与MSForm.CommandButton同名的本地创建类的例子:
以及在这种情况下TypeName和TypeOf的工作方式:
Option Explicit
Private m_buttonMsForms As MSForms.CommandButton
Private m_buttonLocal As CommandButton
Private Sub UserForm_Initialize()
Set m_buttonMsForms = Me.Controls.Add( _
"Forms.CommandButton.1", "testMsButton", True)
Set m_buttonLocal = New CommandButton
m_buttonLocal.Name = "testLocalButton"
Debug.Print "We have two instances of two different button types: " & _
m_buttonLocal.Name & " and " & m_buttonMsForms.Name
' Check instances with TypeName function
' TypeName function returns same results
If VBA.TypeName(m_buttonMsForms) = VBA.TypeName(m_buttonLocal) Then
Debug.Print "TypeName of both buton types returns same result"
End If
' Check instances with TypeOf operator
' TypeOf doen't work with not initialised objects
If m_buttonLocal Is Nothing Or m_buttonMsForms Is Nothing Then _
Exit Sub
' TypeOf operator can distinguish between
' localy declared CommandButton type and MSForms CommandButton
If TypeOf m_buttonLocal Is MSForms.CommandButton Then _
Debug.Print "m_buttonLocal Is MSForms.CommandButton"
If TypeOf m_buttonMsForms Is CommandButton Then _
Debug.Print "m_buttonMsForms Is CommandButton"
If TypeOf m_buttonLocal Is CommandButton Then _
Debug.Print "m_buttonLocal Is CommandButton"
If TypeOf m_buttonMsForms Is MSForms.CommandButton Then _
Debug.Print "m_buttonMsForms Is MSForms.CommandButton"
End Sub
Output:
We have two instances of two different button types: testLocalButton and testMsButton TypeName of both buton types returns same result m_buttonLocal Is CommandButton m_buttonMsForms Is MSForms.CommandButton
数字1和3创建了相同类型的控件。第一个语句只是完全限定 - 等同于使用Dim ws as WorkSheet或Dim ws as Excel.WorkSheet。
我不熟悉第二种类型 -“Control.CommandButton” - 并且它在Excel 2010中的用户窗体中无法编译。