Question

我发现在VS2010实际发布之前，this answer被问及并回答了问题。

他们说

VB9只有单行匿名功能。我们正在添加完整的声明和VB10中的多行lambda。

但我尝试添加此代码

 Dim test2 = Function(t1 As T, t2 As T) (
 Dim val1 As IComparable = DirectCast(prop.GetValue(t1), IComparable)
 Dim val2 As IComparable = DirectCast(prop.GetValue(t2), IComparable)
 Return val1.CompareTo(val2)
 )

到Visual Studio 2010中的.NET Framework 4.0项目，它不能编译。

如果这个功能真的实现了，我做错了吗？

Answer 1

我相信你只是错过了'结束功能'系列。试试这个：

 Dim test2 = (Function(t1 As T, t2 As T)
 Dim val1 As IComparable = DirectCast(prop.GetValue(t1), IComparable)
 Dim val2 As IComparable = DirectCast(prop.GetValue(t2), IComparable)
 Return val1.CompareTo(val2)
 End Function)

Answer 2

您缺少End Function，并且您试图将函数体括在括号中，这是错误的。这应该有效：

Dim test2 = Function(t1 As T, t2 As T)
    Dim val1 As IComparable = DirectCast(prop.GetValue(t1), IComparable)
    Dim val2 As IComparable = DirectCast(prop.GetValue(t2), IComparable)
    Return val1.CompareTo(val2)
End Function

此功能记录在此处：

Lambda Expressions (Visual Basic)

Answer 3

以下是您可能会觉得有用的内容。注意如何立即调用声明的方法。

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

VB.NET和Visual Studio 2010是否支持多行匿名方法？

3 个答案: