Excel 为什么子例程的第一个参数必须通过VAL传递

我有以下代码：

Sub AddValidation()
   Dim ws, wsDefinitions As Worksheet
   Set ws = ThisWorkbook.Worksheets("TData")
   Set wsDefinitions = ThisWorkbook.Worksheets("Definitions")

   Call AddValidator(ws, wsDefinitions, "FaultType", FaultTypeColumn)
End Sub

及

在编译过程中，我得到AddValidator-ws的第一个参数的ByRef参数类型missmatch。 将ByVal添加到定义中时：

Sub AddValidator(ByVal targetWs As Worksheet, definitionsWs As Worksheet, definitionTableName As String, targetColumnNumber)

一切都很好。AddValidator宏的两个第一个参数是工作表类型，但只需要通过值传递第一个参数

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有人能告诉我为什么吗？

问题在于变量的声明

Dim ws, wsDefinitions As Worksheet

在这里，ws被声明为variant而不是sheet对象，因此Excel会提示您更新参数。如果您解决了这个问题，那么Excel不会引发错误。以下子系统将正常工作

Sub Test()
    Dim ws1 As Worksheet, ws2 As Worksheet
    Set ws1 = ThisWorkbook.Sheets("Sheet1")
    Set ws2 = ThisWorkbook.Sheets("Sheet2")
    mySub ws1, ws2
End Sub
Sub mySub(targetWS As Worksheet, sourceWS As Worksheet)
    MsgBox targetWS.Name
    MsgBox sourceWS.Name
End Sub

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尝试声明这两种变量类型：Dim ws作为工作表，wsDefinitions作为工作表。非常感谢。这就是答案。我认为Dim var1、var2作为工作表将两个变量都声明为工作表，但显然不是。我的过错和误解。

Sub Test()
    Dim ws1 As Worksheet, ws2 As Worksheet
    Set ws1 = ThisWorkbook.Sheets("Sheet1")
    Set ws2 = ThisWorkbook.Sheets("Sheet2")
    mySub ws1, ws2
End Sub
Sub mySub(targetWS As Worksheet, sourceWS As Worksheet)
    MsgBox targetWS.Name
    MsgBox sourceWS.Name
End Sub