vb.net – 当COM属性不正确/丢失时,编译器不会出错？

Public vizSvrEmp As VizualServer.Employees
Set vizSvrEmp = New VizualServer.Employees

Fn = FreeFile
Open vizInfo.Root & "FILE.DAT" For Random As #Fn Len = RecLen
Do While Not EOF(Fn)
    Get #Fn,ClkRecord
    With vizSvrEmp
        Index = .Add(ClkRecord.No)
        .NotAvailable(Index) = ClkRecord.NotAvailable
        .Bananas(Index) = ClkRecord.Start
        'Plus lots more properties
    End With
Loop

我知道你已经在Hans的帮助下解决了这个问题但是为了完整性,使用ClassInterface(ClassInterfaceType.AutoDual)的替代方法是使用ClassInterface(ClassInterfaceType.None)然后实现一个用InterfaceType修饰的显式接口( ComInterfaceType.InterfaceIsDual)取代.

这是更多的工作,但让您完全控制接口GUID.编译时,AutoDual将自动为接口生成唯一的GUID,这样可以节省时间,但是您无法控制它们.

在使用中,这看起来像这样：

<ComVisible(True),_
Guid(Guids.IEmployeeGuid),_
InterfaceType(ComInterfaceType.InterfaceIsDual)> _
Public Interface IEmployee 

   <DispIdAttribute(1)> _
   ReadOnly Property FirstName() As String

   <DispIdAttribute(2)> _
   ReadOnly Property LastName() As String

   <DispIdAttribute(3)> _
   Function EtcEtc(ByVal arg As String) As Boolean

End Interface


<ComVisible(True),_
Guid(Guids.EmployeeGuid),_
ClassInterface(ClassInterfaceType.None)> _
Public NotInheritable Class Employee
   Implements IEmployee 

   Public ReadOnly Property FirstName() As String Implements IEmployee.FirstName
      Get
         Return "Santa"
      End Get
   End Function

   'etc,etc

End Class

请注意如何声明GUID.我发现创建一个帮助类来整合GUID并提供Intellisense很好的工作：

Friend Class Guids
   Public Const AssemblyGuid As String = "BEFFC920-75D2-4e59-BE49-531EEAE35534"   
   Public Const IEmployeeGuid As String = "EF0FF26B-29EB-4d0a-A7E1-687370C58F3C"
   Public Const EmployeeGuid As String = "DE01FFF0-F9CB-42a9-8EC3-4967B451DE40"
End Class

最后,我在汇编级别使用它们：

'The following GUID is for the ID of the typelib if this project is exposed to COM
<Assembly: Guid(Guids.AssemblyGuid)> 

'NOTE:  The following attribute explicitly hides the classes,methods,etc in 
'        this assembly from being exported to a TypeLib.  We can then explicitly 
'        expose just the ones we need to on a case-by-case basis.
<Assembly: ComVisible(False)> 
<Assembly: ClassInterface(ClassInterfaceType.None)>