重载属性

发布于 2024-10-21 13:15:06 字数 468 浏览 7 评论 0原文

我尝试在类模块内的 VBA 中重载：

Dim a As Integer

Public Property Let SomeNumber(newNumber as Integer)
   a = newNumber
End Property
Public Property Let SomeNumber(newNumber as String)
   a = Val(newNumber)
End Property
Public Property Get SomeNumber() As Integer
   SomeNumber = a
End Property

编译器抱怨“检测到不明确的名称”，其中显然存在不同的签名。是否可以重载 VBA 或 VB6 类中定义的属性？如果是这样，语法是什么？

此外，如果不可能进行属性重载，那么除了以更无缝的方式访问实例化对象的字段之外，属性相对于公共函数定义的 get/set 方法还有什么好处呢？

原文

I tried to overload in VBA within a class module:

Dim a As Integer

Public Property Let SomeNumber(newNumber as Integer)
   a = newNumber
End Property
Public Property Let SomeNumber(newNumber as String)
   a = Val(newNumber)
End Property
Public Property Get SomeNumber() As Integer
   SomeNumber = a
End Property

The compiler complains that an "ambiguous name was detected" where clearly there is a different signature. Is it possible to overload a property defined within a class in VBA or VB6? If so, what would be the syntax?

Moreover, if property overloading is not possible, what benefits do properties offer over get/set methods defined by public functions other than a more seamless way to access the fields of an instantiated object?

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小兔几 2024-10-28 13:15:06

您可以使用变体或对象类型并手动处理类型检查吗？

可选参数的混合也是可能的，但它并不完全等同于重载。

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梦晓ヶ微光ヅ倾城 2024-10-28 13:15:06

不可以。

解决方法是使用变体，它允许客户端传递任何内容。但是您必须编写代码来在运行时进行类型检查：

Public Property Let SomeNumber(newNumber as Variant)
   Select Case VarType(newNumber) 
      Case vbInteger         '' Caller passed an integer
        a = newNumber
      Case vbString          '' Caller passed a string
        a = Val(newNumber)
      Case Else
        Err.Raise vbObjectError+513, , "Invalid type passed"
      End Select
End Property
Public Property Get SomeNumber() As Variant
   SomeNumber = a
End Property

有关更多详细信息，请参阅 Dan Appleman 的优秀书籍在 Visual Basic 6 中开发 COM/ActiveX 组件。

No.

The workaround is to use Variants, which allows the client to pass anything. But you have to write code to do the type-checking at runtime:

Public Property Let SomeNumber(newNumber as Variant)
   Select Case VarType(newNumber) 
      Case vbInteger         '' Caller passed an integer
        a = newNumber
      Case vbString          '' Caller passed a string
        a = Val(newNumber)
      Case Else
        Err.Raise vbObjectError+513, , "Invalid type passed"
      End Select
End Property
Public Property Get SomeNumber() As Variant
   SomeNumber = a
End Property

For more details see Dan Appleman's excellent book Developing COM/ActiveX Components In Visual Basic 6.

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