在函数中使用时,阴影表现为奇数

Question

在谈论阴影和重载时,我知道VB.net非常奇怪,但是这个我完全感到困惑.

我正在使用类似于以下模型的模型.家长班:

Public Class Base
    Function F() As String
        Return "F() in Base Class"
    End Function

    Function F(ByVal n As Integer) As String
        Return "F(" + n.ToString() + ") in Base Class"
    End Function
End Class

还有这个:

Class Derived
    Inherits Base
    Shadows Function F() As String
        Return "-"
    End Function
End Class

运行以下内容时:

Sub Main()
    Dim parent As Base = New Base()
    Dim child As Derived = New Derived()

    Console.WriteLine(parent.F())
    Console.WriteLine(parent.F(1))
    Console.WriteLine("------------")

    Console.WriteLine(child.F())
    Console.WriteLine(child.F(1)) 'this should not compile, due to the shadow keyword.

    Console.Read()
End Sub

抛出IndexOutOfRangeException.此外,在更改时(在派生类中):返回" - "表示返回"派生类中的Func"控制台打印字符"u".有人知道这个的原因吗？

Answer 1

你的F是一个字符串,所以当你指定索引时,它会查看字符串的索引,而不是带有整数参数的第二个函数.

"u"是"Func"中的第二个字符,由索引1指定.

对于您的示例,您还必须隐藏第二个函数:

Class Derived
  Inherits Base

  Shadows Function F() As String
    Return "-"
  End Function

  Shadows Function F(ByVal n As Integer) As String
    Return "X"
  End Function
End Class