如何更换末端

VB中错误管理和恢复的标准方法是使用 On Error

引发的错误将在调用堆栈中向上移动,直到它碰到通过定义了错误处理程序的函数为止 出错时 ,或直到调用堆栈为空,此时程序将终止并出现错误。

所以如果你更换 End 具有 Err.Raise MSDN 在VBA上,由于MS非常小心地删除了实际的VB语言引用,因此可以执行以下操作:

Option Explicit

' you don't need to, but it's good style to have meaningful error numbers
' (vbObjectError is the error number after which user-defined errors may exist)
Const MY_ERROR_TYPE_A As Integer = vbObjectError + 1
Const MY_ERROR_TYPE_B As Integer = vbObjectError + 2

Public Sub Button_Click()
  On Error GoTo Err_Button_Click

  Call DoSomething

  Exit Sub

Err_Button_Click:
  Select Case Err.Number
    Case MY_ERROR_TYPE_A:
      MsgBox "Error during Button_Click: " & vbNewLine & _
        Err.Description & vbNewLine & _
        "in " & Err.Source, vbExclamation, "Oops"
      Err.Clear
      Resume Next
    Case MY_ERROR_TYPE_B:
      MsgBox Err.Description, vbCritical, "This is really bad."
      End
  End Select
End Sub

Public Sub DoSomething()
  Call DoThing_1
  Call DoThing_2
End Sub

Public Sub DoThing_1()
  Dim frob

  Call DoThing_A
  '...
  Call DoThing_B
  '...
  If frob = 0 Then
    Err.Raise MY_ERROR_TYPE_A, "DoThing_1", "Could not frob the buzz"
  End If
  '...
  Call DoThing_C
  '...
End Sub

在这里 Button_Click 定义错误处理程序。通常,这是一个代码块,只能由某个标签访问,即存在一个 Exit Sub / Exit Function 在它前面,你需要 GoTo 去那里。在该块中,您可以向用户显示有意义的消息,并通过 Resume Next

它不必像上面的示例那样详细。你可以实现它的一个最小版本-没有错误常量,没有消息,只是 呃,升起 和

我在这里遵循的模式是将sub改为函数,并让每个sub返回一个true/false值,指示程序是否应该继续。另外,存储错误的全局变量也可以工作,但我更喜欢带有错误消息的out参数。

所以,如果我们使用我的模式,你的代码会变成:

Private Sub Button_Click()
  Call DoSomething()
End Sub

Public Sub DoSomething()
    Dim strErrDescription as String
    If DoThing_1(strErrDescription) Then
        If DoThing_2(strErrDescription) Then
            //Could put a DoThing_3() 'here if desired
        End If
    End if
    'Do something with strErrDescription now
End Sub

'Returns true if we should continue, false if an error happened and we should stop
Public Function DoThing_1(ByRef strErrorDescriptionOut) as Boolean 
  DoThing_1 = True 'Callers continue unless we encounter an error
  Call DoThing_A() 'Note: If you want to follow the same pattern, you can add an if here as well
  ...
  Call DoThing_B() 'Note: If you want to follow the same pattern, you can add an if here as well
  ...
  strErrorDescriptionOut = "Error Here"
  'End  
  DoThing_1 = false
  Exit Function 
  ...
  Call DoThing_C()
  ...
End Function