.net - 私有(private)嵌套类

Question

我想创建一个只能对父类可见和实例化的嵌套类。
但我也希望能够通过父类的公共(public)变量来使用嵌套类的实例。
我尝试将嵌套类设为私有(private)，或将嵌套类的构造函数设为私有(private)，但它不会编译。
是否可以在 .NET 中执行此操作？

这可以编译并且可以工作，但是任何人都可以使用嵌套类:

 Public Class OuterClass
        Public X As Integer = 123
        Public NestedClassInstance As New NestedClass(Me)

        Public Class NestedClass
            Private Parent As OuterClass

            Public Sub New(ByVal _Parent As OuterClass)
                Parent = _Parent
            End Sub

            Public Sub GetParentX()
                Debug.WriteLine("X = " & Parent.X.ToString)
            End Sub
        End Class
    End Class

    Sub Main()
        Dim OuterClassInstance As New OuterClass
        OuterClassInstance.NestedClassInstance.GetParentX()
    End Sub

Answer 1

通常 Private 嵌套类实现一个接口(interface)或继承另一个类，并暴露接口(interface)/基类。当您想隐藏父类的实现时，这很有用。像这样的东西:

Module EntryPoint
    Sub Main()
        Dim OuterClassInstance As New OuterClass
        OuterClassInstance.NestedClassInstance.GetParentX()
    End Sub
End Module

Public Class OuterClass
    Public X As Integer = 123
    Public NestedClassInstance As ISomeImplementation = New NestedClass(Me)

    Private Class NestedClass
        Implements ISomeImplementation
        Private Parent As OuterClass

        Public Sub New(ByVal _Parent As OuterClass)
            Parent = _Parent
        End Sub

        Public Sub GetParentX() Implements ISomeImplementation.GetParentX
            Debug.WriteLine("X = " & Parent.X.ToString)
        End Sub
    End Class
End Class

Public Interface ISomeImplementation
    Sub GetParentX()
End Interface