Question

[编辑代码] 对不起新手问题。我试图在VBA for Excel中测试嵌套类但收到错误消息。谁能帮我理解为什么？谢谢！

内部课程：

' CLASS MODULE - cInside
' Member variables
Private m_Value As Integer

' Properties
Property Get Value() As Integer
    Value = m_Value
End Property

Property Let Value(i As Integer)
    m_Value = i
End Property

' Methods
Sub init()
    m_Value = 0
End Sub

Sub Inc()
    m_Value = m_Value + 1
End Sub

课外：

' CLASS MODULE - cOutside
' Member variables
Private m_Num1 As New cInside
Private m_Num2 As New cInside

' Properties
Property Get Num1() As cInside
    Num1 = m_Num1.Value
End Property

Property Get Num2() As cInside
    Num2 = m_Num2.Value
End Property

Property Set Num1(i As cInside)
    Set m_Num1 = i
End Property

Property Set Num2(i As cInside)
    Set m_Num2 = i
End Property

主程序：

Sub Main()

Dim o As New cOutside
Dim i As New cInside

i.Value = 9
i.Inc
Debug.Print i.Value '<-- this works

Set o.Num1 = i
o.Num1.Inc  '<-- object variable or with block variable not set
Debug.Print (o.Num1.Value)

End Sub

再次感谢你！

Answer 1

n.Num1会返回Integer，这不是cInside的实例，因此没有Inc成员，这使其成为编译器抱怨的无效限定符; - ）

你的cOutside课程需要以某种方式揭露它：

Property Get ComposedObject1() As cInside
    Set ComposedObject1 = m_Num1
End Property

然后调用代码可以这样做：

n.ComposedObject1.Inc

我把它称为“组合”，因为你所做的不是“嵌套”，而是“组成”。 VBA不支持嵌套类，嵌套类是在另一个类模块中定义的类模块，如下所示：

Class Outside
    '... members...

    Class Inside
        '...members...
    End Class
End Class

VB.NET可以做到这一点，但在VBA 1类模块中只能定义1个类。

VBA - 嵌套类

1 个答案: