泛型和Com可见.NET库 [英] Generics and Com Visible .NET libraries

问题描述

我开发了一个VB.NET库（部分开发在C＃上），这在很大程度上依赖于从一个抽象通用基类继承，我试图找出这个的最佳实践。我很遗憾必须使用框架3.5。

 公共MustInherit类MyBaseClass（Of T）
公共
结束类
 
公共类MyDerivedClass 
 Inherits MyBaseClass（Of String）
 
私有_myProperty作为字符串
 
公共属性MyProperty As String 
 Get 
返回_myProperty 
结束Get 
设置（值为字符串）
 _myProperty =值
结束集
结束属性
结束类
  

我在VBA中使用.tlb文件作为参考我运行以下代码：

  Dim m As New VBtoVBA.MyDerivedClass 
 m.MyProperty =foo
  

我收到错误运行时错误430：类不支持自动化或不支持预期的接口。

另一方面，我将第一行改为：

 公共MustInherit类MyBaseClass 
公共无关作为字符串
结束类
 
公共类MyDerivedClass 
继承MyBaseClass 
  

VBA脚本工作。因此，我认为问题是与泛型（也记录在其他来源）。然而，删除我的库的通用功能是不可能的。我可以想到的最好的解决方法是写一个第三个类，包括MyDerivedClass作为一个字段，并作为一个非通用接口：

 公共类MyDerivedClassString 
 
私人_innerObj作为新的MyDerivedClass 
 
公共属性MyProperty作为字符串
获取
返回_innerObj.MyProperty 
 End Get 
 Set（value As String）
 _innerObj.MyProperty = value 
 End Set 
 End Property 
 
公共属性Whatever As String 
 Get 
返回_innerObj.Whatever 
结束Get 
设置（值为字符串）
 _innerObj.Whatever =值
结束集
结束属性
 
结束类
  

这样我就可以使用它， d喜欢在VBA：

  m.Whatever =wha
 MsgBox（m.Whatever）
 

顺便说一下，我认为可能有另一种（更好的）方式来实现相同的结果，我真的希望因为m库是由几十个类组成的。

非常感谢。

解决方案

正如我在注释写入库（dll）MS Office应用程序是位...硬编码。这个dll必须暴露方法和属性，以便能够在COM自动化中使用它。为了能够实现这一点，你需要编写接口：

 命名空间VBtoVBA 
 public Interface IMyDerivedClass 
属性MyProperty as String 
结束接口
结束命名空间
  

DerivedClass

  Public Class MyDerivedClass 
 Inherits MyBaseClass（Of String）
实现IMyDerivedClass 
 
 Private _myProperty As String 
 
公共属性MyProperty As String实现IMyDerivedClass.MyProperty 
  

现在，转到项目属性窗口
1）选择应用程序选项卡 - 单击装配信息按钮，在下一个窗口中选择使装配COM可见复选框（使用 code>按钮），

2）选择编译标签 - 选择注册COM interop checkbox

3）保存项目和Build dll

4）现在，在Office应用程序中转到VBA代码编辑器 - > 引用菜单。 参考窗口添加对 yourDllName.tlb

的引用

现在，您可以在Office应用程序中使用您的dll;）

我测试的代码：

 code>选项显式
 
 Sub DoSomething（）
 Dim m As VBtoVBA.MyDerivedClass 
 
设置m =新VBtoVBA.MyDerivedClass 
 
 m.MyProperty =Something
 
 MsgBox m.MyProperty 
 
 
 End Sub 
  

它的工作原理）

I've developed a VB.NET library (partially developed on C# as well) that heavily depends on inheriting from an abstract generic base class, and I'm trying to figure out the best practice for this. I Sadly have to do it using framework 3.5.

Public MustInherit Class MyBaseClass(Of T)
  Public Whatever As T
End Class

Public Class MyDerivedClass
  Inherits MyBaseClass(Of String)

  Private _myProperty As String

  Public Property MyProperty As String
    Get
      Return _myProperty
    End Get
    Set(value As String)
      _myProperty = value
    End Set
  End Property
End Class

I attach the .tlb file as a reference in VBA (using Excel), and I run the following code:

Dim m As New VBtoVBA.MyDerivedClass
m.MyProperty = "foo"

And I get the error "Run-time error 430: Class does not support Automation or does not support expected interface".

On the other hand, I change the first lines to:

Public MustInherit Class MyBaseClass
  Public Whatever As String
End Class

Public Class MyDerivedClass
  Inherits MyBaseClass

The VBA script works. Hence I assume the issue is with generics (as documented in other sources as well). Dropping the generic feature of my library is not possible, though. The "best" workaround I can think of is to write a third class that includes MyDerivedClass as a field, and works as a non-generic interface to it:

Public Class MyDerivedClassString

  Private _innerObj As New MyDerivedClass

  Public Property MyProperty As String
    Get
      Return _innerObj.MyProperty
    End Get
    Set(value As String)
      _innerObj.MyProperty = value
    End Set
  End Property

  Public Property Whatever As String
    Get
      Return _innerObj.Whatever
    End Get
    Set(value As String)
      _innerObj.Whatever = value
    End Set
  End Property

End Class

This way I can work with it pretty much as I'd like to in VBA:

m.Whatever = "wha"
MsgBox (m.Whatever)

By the way I think that there might be another (better) way to achieve the same result, and i really hope so since m library is made up of dozens of classes.

Many thanks.

解决方案

As i mentioned in comment writing library (dll) for MS Office applications is bit... hard-coded. This dll must exposes methods and properties to be able to use it in COM automation. To be able to achieve that, you need to write interface(s):

Namespace VBtoVBA
    Public Interface IMyDerivedClass
        Property MyProperty As String
    End Interface
End Namespace

then in DerivedClass

Public Class MyDerivedClass
    Inherits MyBaseClass(Of String)
    Implements IMyDerivedClass

    Private _myProperty As String

    Public Property MyProperty As String Implements IMyDerivedClass.MyProperty

Now, go to Project Properties window 1) choose Application tab - click on Assembly Information button and in the next window select Make assembly COM visible checkbox (apply setting using OK button),

2) choose Compile tab - select Register for COM interop checkbox

3) Save project and Build dll

4) Now, go to VBA Code editor in Office application -> References menu. In Reference window add reference to yourDllName.tlb

Now, you can use your dll in Office application ;)

I tested code:

Option Explicit

Sub DoSomething()
Dim m As VBtoVBA.MyDerivedClass

Set m = New VBtoVBA.MyDerivedClass

m.MyProperty = "Something"

MsgBox m.MyProperty


End Sub

and it works as well ;)

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