如何将委托从 c# 转换为 vb.net？

Question

我有这段代码，我正在尝试从 C# 转换为 VB.net：

public object Invoke(object instance, object[] inputs, out object[] outputs)
        {
            // Create a new, STA thread
            object[] staOutputs = null;
            object retval = null;
            Thread thread = new Thread(
                delegate(){
                    retval = _innerInvoker.Invoke(instance, inputs, out staOutputs);
                });
            thread.SetApartmentState(ApartmentState.STA);
            thread.Start();
            thread.Join();
            outputs = staOutputs;
            return retval;
        }

整个代表的事情让我失望。谁能帮我转换一下？或者有没有解释如何做到这一点的文章？

Answer 1

这是一个匿名函数，而 VB.Net 不支持这样的匿名函数（假设 .Net 2.0，因为在 .Net 3.5 中将被写为 lambda 表达式）。

您可以在 VB.Net 中做的最好的事情是将匿名函数（委托）作为一个单独的方法添加到同一类中，并使用 AddressOf 运算符来引用这个新方法。

---

更新：
再次阅读您的代码，翻译很复杂，因为您的匿名方法将被解释为 closure，这意味着 C# 编译器在将代码转换为 IL 之前会对代码进行复杂的转换；创建一个全新的类是为了捕获（关闭）方法中引用的局部变量：

Class InnerInvokerClosure
    Public instance As Object
    Public inputs() As Object
    Public staOutputs() As Object
    Public retValue As Object

    Public _innerInvoker As SomeDelegateType

    Sub New(ByRef instance as Object, ByRef inputs() as Object, ByRef staOutputs() As Object, ByRef retValue As Object, ByRef _innerInvoker As SomeDelegateType)
        Me.instance = instance
        Me.inputs = inputs
        Me.staOoutputs = staOutputs
        Me.retValue = retValue

        Me._innerInvoker = _innerInvoker
    End Sub

    Public Function Invoke() As Object
        retValue = _innerInvoker.Invoke(instance, inputs, staOutputs);
    End Function

End Class

Public Function Invoke(ByVal instance As Object, ByVal inputs() as Object, ByRef outputs() As Object) As Object
    Dim closure As New InnerInvokerClosure(instance, inputs, Nothing, Nothing, _innerInvoker)

    Dim t As New Thread(AddressOf closure.Invoke)
    t.SetApartmentState(ApartmentState.STA)
    t.Start()
    t.Join()

    outputs = closure.staOutputs
    return closure.retValue      
End Function

请注意，此翻译未经测试，可能是错误的：确切的转换可能非常复杂。

Answer 2

我最喜欢的方法是在 C# 中编译，然后使用反射器查看它在其他 dotNET 语言中的样子。

Friend Class Program
' Methods '
Private Shared Function Foo(ByVal instance As Object, ByVal inputs As Object(), <Out> ByRef outputs As Object()) As Object
    outputs = Nothing
    Return Nothing
End Function

Public Function Invoke(ByVal instance As Object, ByVal inputs As Object(), <Out> ByRef outputs As Object()) As Object
    Dim staOutputs As Object() = Nothing
    Dim retval As Object = Nothing
    Dim thread As New Thread(Function 
        retval = Me._innerInvoker.Invoke(instance, inputs, staOutputs)
    End Function)
    thread.SetApartmentState(ApartmentState.STA)
    thread.Start
    thread.Join
    outputs = staOutputs
    Return retval
End Function

' Fields '
Private _innerInvoker As MyInvoker = New MyInvoker(AddressOf Program.Foo)
End Class


<CompilerGenerated> _
Private NotInheritable Class <>c__DisplayClass1
' Methods '
Public Sub <Invoke>b__0()
    Me.retval = Me.<>4__this._innerInvoker.Invoke(Me.instance, Me.inputs, Me.staOutputs)
End Sub


' Fields '
Public <>4__this As Program
Public inputs As Object()
Public instance As Object
Public retval As Object
Public staOutputs As Object()
End Class

Answer 3

这是我使用的最终代码：

    Public Function Invoke(ByVal instance As Object, ByVal inputs As Object(), ByRef outputs As Object()) As Object Implements System.ServiceModel.Dispatcher.IOperationInvoker.Invoke
        Dim staOutputs As Object() = Nothing
        Dim retval As Object = Nothing
        Dim thread As New Thread(AddressOf DoWork)
        _instance = instance
        _inputs = inputs
        _staOutPuts = staOutputs
        thread.SetApartmentState(ApartmentState.STA)
        thread.Start()
        thread.Join()
        outputs = staOutputs
        Return retval
    End Function

    Private Function DoWork() As Object
        Return _innerInvoker.Invoke(_instance, _inputs, _staOutPuts)
    End Function

@Rune FS - 如此接近，只需要一点帮助。谢谢！

Answer 4

应该是这样的：（其中 _ 是私有字段（这不是生产 rdy，但希望完全给你这个想法）

Public Function Invoke(instance As Object, inputs As Object(), ByRef outputs As Object()) As Object
        ' Create a new, STA thread
        Dim staOutputs As Object() = Nothing
        Dim retval As Object = Nothing
        Dim thread As New Thread(AddressOf(Do))

        _instance = instance
        _inputs = inputs
        _staOutPuts = staOutputs
        thread.SetApartmentState(ApartmentState.STA)
        thread.Start()
        thread.Join()
        outputs = staOutputs
        Return retval
    End Function

    private Function Do() as Object
    Return _innerInvoker.Invoke(_instance, _inputs, _staOutputs)
    end Function

Answer 5

有一个在线 C# 到 VB 转换器（反之亦然）位于 http://converter.telerik.com/

我把你的代码贴在那里....我不知道这是否是有效的 VB 或者它是否可以工作，但你可以试一试。

Public Function Invoke(instance As Object, inputs As Object(), ByRef outputs As Object()) As Object
    ' Create a new, STA thread
    Dim staOutputs As Object() = Nothing
    Dim retval As Object = Nothing
    Dim thread As New Thread(Function() Do
        retval = _innerInvoker.Invoke(instance, inputs, staOutputs)
    End Function)
    thread.SetApartmentState(ApartmentState.STA)
    thread.Start()
    thread.Join()
    outputs = staOutputs
    Return retval
End Function