vb.net – 为什么在从同一个类的共享函数调用时,无法访问重载的

编辑

这个问题并不是要回答应该采取什么措施来解决它.我知道修复.我想要解释为什么编译器会做它的功能.防爆.在这种情况下,是否考虑了私有功能？

问题

我有一个类,它有一个名为WhatIs的公共共享(静态)函数. WhatIs采用具有对象集合的参数.代码遍历此集合并调用具有参数匹配类型的WhatIs函数.

执行时,抛出InvalidCastException异常,因为执行试图调用启动它的WhatIs函数,而不是所提供类型的函数.

这很奇怪,但是让我感到奇怪的是当你将私有共享函数更改为public共享时,它工作正常.

甚至更奇怪,当你明确地施放对象时,即使该函数是私有的,它也能工作.

什么？！有人请解释一下

码

胆量：

Public Class House
    Public Property Furniture As ICollection(Of Object)

    Public Sub New()
        Furniture = New List(Of Object)
    End Sub
End Class

Public Class Chair
    Public Property IsComfortable As Boolean
End Class

Public Class Table
    Public Seats As Integer
End Class

Public Class HouseExaminer
    Public Shared Function WhatIs(thing As House) As String
        Dim isA As String = "a house that contains "

        For Each item In thing.Furniture
            isA &= WhatIs(item)
        Next

        Return isA
    End Function

    Private Shared Function WhatIs(thing As Chair) As String
        Return "a " & If(thing.IsComfortable,"comfortable","uncomfortable") & " chair "
    End Function

    Private Shared Function WhatIs(thing As Table) As String
        Return "a table that seats " & thing.Seats & " iguanas"
    End Function
End Class

去测试

Imports System.Text
Imports Microsoft.VisualStudio.TestTools.UnitTesting
Imports stuff

<TestClass()>
Public Class HouseExaminerTests

    <TestMethod()>
    Public Sub TestWhatIs()
        Dim given As New House()
        Dim expected As String
        Dim actual As String

        given.Furniture.Add(New Chair() With {.IsComfortable = True})
        given.Furniture.Add(New Table() With {.Seats = 4})

        expected = "a house that contains a comfortable chair a table that seats 4 iguanas"
        actual = HouseExaminer.WhatIs(given)

        Assert.Equals(expected,actual)
    End Sub
End Class

结果

调试测试,你得到这个：
InvalidCastException的
方法调用失败,因为“公共共享函数WhatIs(thing as stuff.House)As String”无法使用以下参数调用：

参数匹配参数’thing’无法从’Chair’转换为’House’.

这些变化使它工作,但为什么？！

让他们公开

将HouseExaminer中的私有共享功能更改为public,重新运行测试.扰流板,它的工作原理

显式地转换对象

将它们更改为私有然后替换

isA &= WhatIs(item)

同

If TypeOf item Is Chair Then isA &= WhatIs(CType(item,Chair))
If TypeOf item Is Table Then isA &= WhatIs(CType(item,Table))

重新运行测试,你知道什么,它的工作原理