다른 반환 형식으로 다형성으로 자식 클래스 사용

Question

기본 클래스 인 BaseParser에서 상속 한 두 가지 파서 클래스가 있습니다. 두 클래스 중 하나를 다른 Monitor 클래스의 매개 변수로 사용하려고합니다. Parser 클래스 인 CS600과 TCH600에는 RawDataList와 SummaryDataList의 두 가지 속성이 있습니다. CS600 클래스의 RawDataList는 (CS600Data의) List를 반환합니다. TCH600 RawDataList는 TCH600Data의 List를 리턴합니다. SummaryDataList는 각 Parser 클래스에서 유사한 클래스를 반환합니다. CS600Data 및 TCH600Data는 기본 클래스 BaseData에서 파생됩니다. BaseParser에는 또한 RawDataList (BaseData의 List) 및 SummaryDataList (BaseSummaryData의 List)가 있습니다.

Monitor 클래스에는 위의 두 가지 구체적인 구문 분석기 중 하나 인 _thisParser가있는 개인 필드가 있습니다. Monitor 클래스 내에서 _thisParser의 RawDataList 및 SummaryDataList를 호출하고 사용할 수 있기를 원하지만 구체적인 파서 클래스를 구성 할 때 Visual Studio에서는 CS600의 RawDataList 속성이 반환 값이 다르므로 BaseParser의 RawDataList 속성을 재정의 할 수 없다고 기록합니다 유형.

CS600Data BaseData에서 파생 된 이후 (뿐만 아니라 자체의 일부 새 속성을 추가합니다) 내가 CS600Data BaseData 사용할 때 사용할 수 있다고 생각. 내가 오해하니? 이 클래스들을 어떻게 올바르게 만들 수 있습니까?

Public MustInherit Class BaseParser 

    Protected _rawDataList As List(Of RawGasData.BaseData) 
    Public MustOverride ReadOnly Property RawDataList() As List(Of RawGasData.BaseData) 

    Protected _summaryDataList As List(Of SummaryGasData.BaseSummaryData) 
    Public MustOverride ReadOnly Property SummaryDataList() As List(Of SummaryGasData.BaseSummaryData) 

    Public Event GasDataCreated(ByVal sender As Object, ByVal e As EventArgs) 

    Public Sub New() 
    End Sub 

    Public Sub New(ByVal dataFilePath As String, ByVal unit As String) 
     Load(dataFilePath, unit) 
    End Sub 

    Public Sub Load(ByVal dataFilePath As String, ByVal unit As String) 
     Dim contents = My.Computer.FileSystem.ReadAllText(dataFilePath) 
     ParseRawData(contents) 
     GenerateSummaryData(contents, unit) 
     RaiseEvent GasDataCreated(Me, EventArgs.Empty) 
    End Sub 

    Protected MustOverride Sub ParseRawData(ByVal fileContents As String) 

    Protected MustOverride Sub GenerateSummaryData(ByVal fileContents As String, ByVal unit As String) 

End Class 

Public Class CS600Parser 
    Inherits BaseParser 

    Shadows _rawDataList As List(Of RawGasData.CS600Data) 
    'Cannot override base class' RawDataList - differ by their return types 
    Public Overrides ReadOnly Property RawDataList() As List(Of RawGasData.CS600Data) 
     Get 
      Return _rawDataList 
     End Get 
    End Property 

    Shadows _summaryDataList As List(Of SummaryGasData.CS600SummaryData) 
    'Cannot override base class' SummaryDataList - differ by their return types 
    Public Overrides ReadOnly Property SummaryDataList() As List(Of SummaryGasData.CS600SummaryData) 
     Get 
      Return _summaryDataList 
     End Get 
    End Property 

    Protected Overrides Sub ParseRawData(ByVal fileContents As String) 
     Dim data = From d In fileContents.Trim.Split(CChar(vbCrLf)) _ 
        Let fields = d.Split(","c).Select(Function(s) s.Trim) _ 
        Select New RawGasData.CS600Data With { _ 
         .SampleNumber = fields(0), _ 
         .UserID = fields(1), _ 
         .CarbonValue = CDbl(fields(2)), _ 
         .SulfurValue = CDbl(fields(3))} 

     _rawDataList = data.ToList 

    End Sub 

    Protected Overrides Sub GenerateSummaryData(ByVal fileContents As String, ByVal unit As String) 
     Dim groupedData = From d In _rawDataList _ 
          Group By d.SampleNumber Into Group _ 
          Select New SummaryGasData.CS600SummaryData With { _ 
          .DataTimeStamp = Now, _ 
          .SampleNumber = SampleNumber, _ 
          .UserID = Group.First.UserID, _ 
          .CarbonAverage = Group.Select(Function(s) s.CarbonValue).Average, _ 
          .CarbonUnit = unit, _ 
          .SulfurAverage = Group.Select(Function(s) s.SulfurValue).Average, _ 
          .SulfurUnit = unit} 

     _summaryDataList = groupedData.ToList 

    End Sub 

End Class 

Public Class TCHParser 
    Inherits BaseParser 

    Shadows _rawDataList As List(Of RawGasData.TCH600Data) 
    'Cannot override base class' RawDataList - differ by their return types 
    Public Overrides ReadOnly Property RawDataList() As List(Of RawGasData.TCH600Data) 
     Get 
      Return _rawDataList 
     End Get 
    End Property 

    Shadows _summaryDataList As List(Of SummaryGasData.TCH600SummaryData) 
    'Cannot override base class' SummaryDataList - differ by their return types 
    Public Overrides ReadOnly Property SummaryDataList() As List(Of SummaryGasData.TCH600SummaryData) 
     Get 
      Return _summaryDataList 
     End Get 
    End Property 

    Protected Overrides Sub ParseRawData(ByVal fileContents As String) 
     Dim data = From d In fileContents.Trim.Split(CChar(vbCrLf)) _ 
     Let fields = d.Split(","c).Select(Function(s) s.Trim) _ 
     Select New RawGasData.TCH600Data With { _ 
      .SampleNumber = fields(0), _ 
      .UserID = fields(1), _ 
      .OxygenValue = CDbl(fields(2)), _ 
      .NitrogenValue = CDbl(fields(3)), _ 
      .HydrogenValue = CDbl(fields(4)), _ 
      .MassUsed = CDbl(fields(5))} 

     _rawDataList = data.ToList 

    End Sub 

    Protected Overrides Sub GenerateSummaryData(ByVal fileContents As String, ByVal unit As String) 
     Dim groupedData = From d In _rawDataList _ 
          Group By d.SampleNumber Into Group _ 
          Select New SummaryGasData.TCH600SummaryData With { _ 
          .DataTimeStamp = Now, _ 
          .SampleNumber = SampleNumber, _ 
          .UserID = Group.First.UserID, _ 
          .OxygenAverage = Group.Select(Function(s) s.OxygenValue).Average, _ 
          .OxygenUnit = unit, _ 
          .NitrogenAverage = Group.Select(Function(s) s.NitrogenValue).Average, _ 
          .NitrogenUnit = unit, _ 
          .HydrogenAverage = Group.Select(Function(s) s.HydrogenValue).Average, _ 
          .HydrogenUnit = unit} 

     _summaryDataList = groupedData.ToList 
    End Sub 


End Class 


Public MustInherit Class BaseData 
    Implements IGasData 

    Private _massUsed As Double 
    Public Property MassUsed() As Double Implements IGasData.MassUsed 
     Get 
      Return _massUsed 
     End Get 
     Set(ByVal value As Double) 
      _massUsed = value 
     End Set 
    End Property 

    Private _sampleNumber As String 
    Public Property SampleNumber() As String Implements IGasData.SampleNumber 
     Get 
      Return _sampleNumber 
     End Get 
     Set(ByVal value As String) 
      _sampleNumber = value 
     End Set 
    End Property 

    Private _userID As String 
    Public Property UserID() As String Implements IGasData.UserID 
     Get 
      Return _userID 
     End Get 
     Set(ByVal value As String) 
      _userID = value 
     End Set 
    End Property 
End Class 

Public Class CS600Data 
    Inherits BaseData 


    Private _carbonValue As Double 
    Public Property CarbonValue() As Double 
     Get 
      Return _carbonValue 
     End Get 
     Set(ByVal value As Double) 
      _carbonValue = value 
     End Set 
    End Property 


    Private _sulfurValue As Double 
    Public Property SulfurValue() As Double 
     Get 
      Return _sulfurValue 
     End Get 
     Set(ByVal value As Double) 
      _sulfurValue = value 
     End Set 
    End Property 

End Class 

Public Class TCH600Data 
    Inherits BaseData 

    Private _oxygenValue As Double 
    Public Property OxygenValue() As Double 
     Get 
      Return _oxygenValue 
     End Get 
     Set(ByVal value As Double) 
      _oxygenValue = value 
     End Set 
    End Property 


    Private _nitrogenValue As Double 
    Public Property NitrogenValue() As Double 
     Get 
      Return _nitrogenValue 
     End Get 
     Set(ByVal value As Double) 
      _nitrogenValue = value 
     End Set 
    End Property 


    Private _hydrogenValue As Double 
    Public Property HydrogenValue() As Double 
     Get 
      Return _hydrogenValue 
     End Get 
     Set(ByVal value As Double) 
      _hydrogenValue = value 
     End Set 
    End Property 

End Class 

Answer 1

재정의 된 목록 속성 같은 RawDataList는 추상 기본 클래스의 유형 (또는 더 나은 아직 IGasData) 및 다형성 (polymorphism)이 작동 할 수 없습니다 파생 클래스를해야한다. BaseData 또는 IGasData 유형의 목록을 만드는 것이 문제를 일으키는 경우 디자인이 Liskov Substitution Principle인지 확인하고 싶을 수 있습니다.

컴파일하고 잘 실행하는 단순화 된 그림 (VB.Net 2010) :

Sub Main  
    Dim parser As BaseParser = New TCHParser() 
    Console.WriteLine(parser) 
End Sub 

Public MustInherit Class BaseData  
    Public Property SampleNumber() As String 
End Class 

Public Class TCH600Data 
    Inherits BaseData 

    Public Property OxygenValue() As Double 
End Class 

Public MustInherit Class BaseParser 
    Public MustOverride ReadOnly Property RawDataList As List(of BaseData) 
End Class 

TCHParser 작품 잘가 RawDataList 속성을 재정의. 또한 추상 기본 클래스가 Protected _rawDataList 필드 인 이유가 확실하지 않습니다. 이를 제거하면 파생 된 유형의 해당 필드를 섀도 잉하는 것에 대해 더 이상 걱정할 필요가 없습니다.

Public Class TCHParser 
    Inherits BaseParser 

    ' Populate the list just so we can test easily. 
    Public Sub New() 
     Dim data As New List(Of BaseData) 
     data.Add(New TCH600Data With { 
      .SampleNumber = "1", _ 
      .OxygenValue = 1.5d }) 

     data.Add(New TCH600Data With { 
      .SampleNumber = "2", _ 
      .OxygenValue = 2.5d }) 

     _rawDataList = data 
    End Sub 

    Private _rawDataList As List(of BaseData) 
    Public Overrides ReadOnly Property RawDataList As List(of BaseData) 
     Get 
      Return _rawDataList 
     End Get 
    End Property 
End Class