只有基础类方法？

Question

有没有一种只有基类的方法？

我有一个使用模块的工作，但这分开了只能由基类使用的功能。

我认为在以下

Public MustInherit Class Token 
    ' Token stuff 
    NotInheritable Shared Function Parse(Of T As Token)(CR As CharReader) As T 
    ' Would also be good to be able to do the following without resorting 
    ' to the reflection based bodgery. 
    Return T.Parser(CR) 
    End Function 
End Class 

Public Class Digit 
    Inherit Token 
    ' Digit Stuff 
    Protected Shared Function Parser(CR As CharReader) As Digit 
    If CR.Current.HasValue = False Then Return Nothing 
     Case Select CR.Value 
     Case "0"c To "9"c 
      Return New Digit(CR.Index,0) 
     Case Else 
     Return False 
     End Select 
    End Function 

行所以现在当

Dim d0 = Token.Parse(Of Digit)(cr) 

但

Dim d1 = Digit. 

不会显示Parse方法。

那么这怎么做呢？ （如果可能的话）

编辑

当前实现 这应该真的是一个基类只能在令牌类

Public Module TokenModule 
    Public Function Parse(Of T As Token)(cr As CharReader) As T 
    ' 
    ' Here Be Nasty Reflection Based Bodge Job 
    ' 
    ' Why? What I want to write. (Call a static method on the generic (constrianed) type  specifier.) 
    ' 
    ' Return T.Parser(cr) 
    ' 
    ' Start Bodgery { 
    Dim tt As T 
    tt = GetType(T).InvokeMember("Parser", 
           Reflection.BindingFlags.InvokeMethod + 
           Reflection.BindingFlags.NonPublic + 
           Reflection.BindingFlags.Static, Nothing, tt, {cr}) 
    Return tt 
    ' } End Bodgery 
End Function 
End Module 

令牌（基地）类

Public MustInherit Class Token 
    Private _Index As Integer 
    Private _Count As Integer 
    Protected Friend Sub New(ByVal Index As Integer, Count As Integer) 
    _Index = Index : _Count = Count 
    End Sub 
    Public ReadOnly Property Index As Integer 
    Get 
     Return _Index 
    End Get 
    End Property 
    Public ReadOnly Property Count As Integer 
    Get 
     Return _Count 
    End Get 
    End Property 
    Protected Shared Function Parser(cr As CharReader) As Token 
    Return Nothing 
    End Function 
End Class 

方法

Digit Class

Public Class Digit 
    Inherits Token.Token 
    Private Sub New(ByVal Index As Integer, Count As Integer) 
    MyBase.New(Index, Count) 
    End Sub 
    Protected Overloads Shared Function Parser(cr As CharReader) As Digit 
    Dim crc = cr.Current 
    If crc.HasValue = False Then Return Nothing 
     Select Case crc.Value 
     Case "0"c To "9"c 
      Return New Digit(cr.Index, 1) 
     Case Else 
      Return Nothing 
     End Select 
    End Function 
End Class 

Answer 1

这种关系真的打破了面向对象的概念。如果父类型提供公共功能，那么孩子也应该（认为孩子是父母）。

您希望的功能类型可以通过组合（数字将包含令牌和代理的实例，无论对该实例调用什么）而非继承来轻松实现。

Answer 2

如果CharReader implements IConvertible，您可以将它转换为System.Convert的其他类型。标准类型如Boolean，String,Char,Int32,Double等实施IConvertible。

Shared Function Parse(Of T As Token)(ByVal CR As CharReader) As T 
    Return DirectCast(Convert.ChangeType(CR, GetType(T)), T) 
End Function 

-

Parse可以通过非公开方式遮蔽它

Protected Shared Shadows Function Parse(ByVal CR As CharReader) As Digit 
        ^
        | 
      (note the Shadows keyword) 

请注意，这仅适用于共享的方法，因为你通过类型名称访问这些被隐藏，不是通过一个实例。

Answer 3

不会显示分析方法。

不确定我关注，但您只关注显示该方法的智能感知。这很容易解决与EditorBrowsableAttribute：

Imports System.ComponentModel 
... 
Class Token 
    Public Shared Sub Parse() 
     '' etc 
    End Sub 
End Class 

Class Digit 
    Inherits Token 

    <EditorBrowsable(EditorBrowsableState.Never)> _ 
    Public Shared Shadows Sub Parse() 
     Token.Parse() 
    End Sub 
End Class