VB.NET 有匿名函数吗？

发布于 2024-07-15 01:09:34 字数 407 浏览 9 评论 0原文

根据我在 google 上找到的信息，VB.NET 只有单语句 lambda，而没有多语句匿名函数。然而，我读到的所有文章都在谈论旧版本的 VB.NET，我找不到比 vs2008 beta 1 或 2 更新的内容。

所以问题是：我怎样才能在 VB.NET 中做到这一点？

C#代码：

private void HandleErrors( Action codeBlock ){
    try{
        codeBlock();
    }catch(Exception e){
        //log exception, etc
    }
}

HandleErrors(() => {
    var x = foo();
    x.DoStuff();
    etc
});

原文

From what I can find on google, VB.NET only has one-statement lambdas, and not multi-statement anonymous functions. However, all the articles I read were talking about old versions of VB.NET, I couldn't find anything more recent than vs2008 beta 1 or 2.

So the question: How can I do this in VB.NET?

C# code:

private void HandleErrors( Action codeBlock ){
    try{
        codeBlock();
    }catch(Exception e){
        //log exception, etc
    }
}

HandleErrors(() => {
    var x = foo();
    x.DoStuff();
    etc
});

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枕花眠 2024-07-22 01:09:34

它在 VB10 中是这样的：

Dim food = New With {
    .ID = 1,
    .Name = "Carrot",
    .Type = (
        Function(name As String)
            If String.IsNullOrEmpty(name) Then Return String.Empty

            Select Case name.ToLower()
                Case "apple", "tomato": Return "Fruit"
                Case "potato": Return "Vegetable"
            End Select

            Return "Meat"
        End Function
    )(.Name)
}
Dim type = food.Type

或者，对应于您的代码：

Sub HandleErrors(codeBlock As Action)
    Try
        codeBlock()
    Catch e As Exception
        ' log exception, etc.
    End Try
End Sub

HandleErrors(Sub()
        Dim x = foo()
        x.DoStuff()
        ' etc.
    End Sub)

It does in VB10:

Dim food = New With {
    .ID = 1,
    .Name = "Carrot",
    .Type = (
        Function(name As String)
            If String.IsNullOrEmpty(name) Then Return String.Empty

            Select Case name.ToLower()
                Case "apple", "tomato": Return "Fruit"
                Case "potato": Return "Vegetable"
            End Select

            Return "Meat"
        End Function
    )(.Name)
}
Dim type = food.Type

Or, corresponding to your code:

Sub HandleErrors(codeBlock As Action)
    Try
        codeBlock()
    Catch e As Exception
        ' log exception, etc.
    End Try
End Sub

HandleErrors(Sub()
        Dim x = foo()
        x.DoStuff()
        ' etc.
    End Sub)

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森罗 2024-07-22 01:09:34

Visual Basic .NET 仅具有 lambda 表达式。

它在当前版本中不支持“匿名委托”，尽管在 VS2010 中它支持（并且在多行中）。

现在唯一的选择是在某处声明您的方法并使用 Addressof 运算符传递它。

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给我一枪 2024-07-22 01:09:34

VB9 只有单行匿名函数。我们在 VB10 中添加完整的语句和多行 lambda。

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墨落画卷 2024-07-22 01:09:34

在此示例中，我有一个操作列表，但只想从 ID 匹配的列表（T 个）中找到一个操作：

Return operations.Find(Function(p) p.OperationID = operationID)

操作 ID 是传递到方法的局部变量，操作是通用列表。

in this example I have a list of operations but only want to find one from a list (of T) where the IDs match:

Return operations.Find(Function(p) p.OperationID = operationID)

operationID is a local variable passed in to the method and operations is a generic list.

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別甾虛僞 2024-07-22 01:09:34

匿名不是委托或函数
它是一种强大的动态类型，

您可以使用泛型函数

Sub Main()
      Dim PersonDynamicType = AnonyFunc(New With {.Name = "david", .Family = "Fisher"})
      Console.Write(PersonDynamicType.Name)
End Sub

Function AnonyFunc(Of t)(v As t) As t
      Return v
End Function

Anonymous isn't a delegate or function
it's a strong dynamical type

you can use generic functions

Sub Main()
      Dim PersonDynamicType = AnonyFunc(New With {.Name = "david", .Family = "Fisher"})
      Console.Write(PersonDynamicType.Name)
End Sub

Function AnonyFunc(Of t)(v As t) As t
      Return v
End Function

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心清如水 2024-07-22 01:09:34

这是不准确的。 VB.NET 实际上有匿名方法。这是一个例子：

Private Function JsonToObject(Of T)(Value As String) As T
    Dim JavaScriptSerializer As New System.Web.Script.Serialization.JavaScriptSerializer()
    Return JavaScriptSerializer.Deserialize(Of T)(Value)
End Function

Dim People As Generic.List(Of Person) = JsonToObject(Of Generic.List(Of Person))(Json)

This is inaccurate. VB.NET does in fact have anonymous methods. Here is an example:

Private Function JsonToObject(Of T)(Value As String) As T
    Dim JavaScriptSerializer As New System.Web.Script.Serialization.JavaScriptSerializer()
    Return JavaScriptSerializer.Deserialize(Of T)(Value)
End Function

Dim People As Generic.List(Of Person) = JsonToObject(Of Generic.List(Of Person))(Json)

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