在 VBA 中克隆对象？

Question

有没有通用的方法在 VBA 中克隆对象？这样我就可以将 x 复制到 y 而不是仅复制指针？

  Dim x As New Class1
  Dim y As Class1

  x.Color = 1
  x.Height = 1

  Set y = x
  y.Color = 2

  Debug.Print "x.Color=" & x.Color & ", x.Height=" & x.Height

我所说的泛型是指Set y = CloneObject(x) 之类的东西，而不必为类创建自己的方法来逐一复制其属性。

Answer 1

我不认为有任何内置的东西，虽然它会很好。

我认为至少应该有一种方法可以使用 VBA 编辑器自动创建克隆方法。等我让孩子们上床睡觉后，我会看看能不能看看……

Answer 2

好的，这是说明它的开始：

创建一个类，叫它，哦，“Class1”：

Option Explicit

Public prop1 As Long
Private DontCloneThis As Variant

Public Property Get PrivateThing()
    PrivateThing = DontCloneThis
End Property

Public Property Let PrivateThing(value)
    DontCloneThis = value
End Property

现在我们需要给它一个克隆函数。在另一个模块中，试试这个：

选项显式

Public Sub makeCloneable()

Dim idx As Long
Dim line As String
Dim words As Variant
Dim cloneproc As String

' start building the text of our new function
    cloneproc = "Public Function Clone() As Class1" & vbCrLf
    cloneproc = cloneproc & "Set Clone = New Class1" & vbCrLf

    ' get the code for the class and start examining it    
    With ThisWorkbook.VBProject.VBComponents("Class1").CodeModule

        For idx = 1 To .CountOfLines

            line = Trim(.lines(idx, 1)) ' get the next line
            If Len(line) > 0 Then
                line = Replace(line, "(", " ") ' to make words clearly delimited by spaces
                words = Split(line, " ") ' so we get split on a space
                If words(0) = "Public" Then ' can't set things declared Private
                    ' several combinations of words possible
                    If words(1) = "Property" And words(2) = "Get" Then
                        cloneproc = cloneproc & "Clone." & words(3) & "=" & words(3) & vbCrLf
                    ElseIf words(1) = "Property" And words(2) = "Set" Then
                        cloneproc = cloneproc & "Set Clone." & words(3) & "=" & words(3) & vbCrLf
                    ElseIf words(1) <> "Sub" And words(1) <> "Function" And words(1) <> "Property" Then
                        cloneproc = cloneproc & "Clone." & words(1) & "=" & words(1) & vbCrLf
                    End If
                End If
            End If
        Next

        cloneproc = cloneproc & "End Function"

        ' put the code into the class
        .AddFromString cloneproc

    End With

End Sub

运行它，然后将以下内容添加到 Class1 中

Public Function Clone() As Class1
Set Clone = New Class1
Clone.prop1 = prop1
Clone.PrivateThing = PrivateThing
End Function

...这看起来像是一个开始。我会清理很多东西（并且可能会 - 这很有趣）。一个很好的正则表达式，用于查找 gettable/lettable/settable 属性，重构为几个小函数，删除旧“克隆”函数的代码（并将新函数放在最后），有点 Stringbuilder-ish to DRY (Don' t Repeat Yourself) 向上串联，诸如此类。

Answer 3

Scott Whitlock 在另一个问题上针对此问题发布了fantastic answer。