VBA类成员函数和类定义问题续第3卷

Question

故事还在继续......我之前的两个问题是关于成员函数

fReadData

和

fReadData2

Public Function fReadData(alue As Range) As Double

    pOne = alue.Cells(1)
    fReadData = pOne
    
End Function

Public Function fReadData2(alue As Range) As ClassOne

    Set fReadData2 = New ClassOne
    
    pOne = alue.Cells(1)
    fReadData2.One = pOne
        
End Function

现在两个版本都可以工作（列表都可以），但现在我想知道为什么下面的

fReadData3

总是给出与

fReadData

或

fReadData2

相同的结果？ 与

fReadData2

相比，唯一的区别是附加变量

foo

。

Public Function fReadData3(alue As Range) As ClassOne
    
    Set fReadData3 = New ClassOne
    Dim foo As Double
    
    foo = alue.Cells(1)
    fReadData3.One = foo
    
    
End Function

一些测试：

函数

Test

已在

Test3

之前运行。

Test3

给出与

Test

相同的值

当

Test2

先于

Test3

运行时，

Test3

给出与

Test2

相同的结果

班级

ClassOne

如下

'ClassOne

Option Explicit

Private pOne As Double


Private Sub Class_Initialize()
    
End Sub


Private Sub Class_Terminate()
    
End Sub


Public Property Get One() As Double
    One = pOne
End Property


Public Property Let One(lOne As Double)
    pOne = lOne
End Property


Public Function fReadData(alue As Range) As Double

    pOne = alue.Cells(1)
    fReadData = pOne
    
End Function


Public Function fReadData2(alue As Range) As ClassOne

    Set fReadData2 = New ClassOne
    
    pOne = alue.Cells(1)
    fReadData2.One = pOne
    
    
End Function

Public Function fReadData3(alue As Range) As ClassOne
    
    Set fReadData3 = New ClassOne
    Dim foo As Double
    
    foo = alue.Cells(1)
    fReadData3.One = foo
    
    
End Function

工作表测试如下

' main module

Option Explicit


Dim oOne As New ClassOne



Function Test(alue As Range) As Double

oOne.fReadData alue

Test = oOne.One

End Function



Function Test2(alue As Range) As Double

oOne.fReadData2 alue

Test2 = oOne.One

End Function

Function Test3(alue As Range) As Double

oOne.fReadData3 alue

Test3 = oOne.One

End Function

Answer 1

哦。

Public Function fReadData3(alue As Range) As ClassOne
  Set fReadData3 = New ClassOne
  Dim foo As Double
  foo = alue.Cells(1)
  fReadData3.One = foo
End Function

Function Test3(alue As Range) As Double
  oOne.fReadData3 alue
  Test3 = oOne.One
End Function

fReadData3 创建新对象并将所需的值分配给该对象，但在 Test3 中你想从另一个对象获取该值。

正确代码：

Function Test3(alue As Range) As Double
  dim tmp
  set tmp = oOne.fReadData3(alue)
  Test3 = tmp.One
End Function