.net - 如何根据创建的子类的类型过滤基类中的对象集合？

Question

我写了这个例子来帮助解释。如您所见，我有一个对象层次结构。我想修改 GetFeatures() 函数以仅返回由我实例化的对象类型的构造函数添加的功能。例如，BasicModel.GetFeatures(new LuxuryModel()) 应该只返回特征“皮革座椅”和“天窗”。如果必须的话，我不介意使用反射。

Public Class Feature

    Public Sub New(ByVal model As BasicModel, ByVal description As String)
        _model = model
        _description = description
    End Sub

    Private _model As BasicModel
    Public Property Model() As BasicModel
        Get
            Return _model
        End Get
        Set(ByVal value As BasicModel)
            _model = value
        End Set
    End Property

    Private _description As String
    Public Property Description() As String
        Get
            Return _description
        End Get
        Set(ByVal value As String)
            _description = value
        End Set
    End Property

End Class


Public Class BasicModel
    Public Sub New()
        _features = New List(Of Feature)
    End Sub

    Private _features As List(Of Feature)

    Public ReadOnly Property Features() As List(Of Feature)
        Get
            Return _features
        End Get
    End Property

    Public Shared Function GetFeatures(ByVal model As BasicModel) As List(Of Feature)
        'I know this is wrong, but something like this...'
        Return model.Features.FindAll(Function(f) f.Model.GetType() Is model.GetType())
    End Function
End Class


Public Class SedanModel
    Inherits BasicModel

    Public Sub New()
        MyBase.New()
        Features.Add(New Feature(Me, "Fuzzy Dice"))
        Features.Add(New Feature(Me, "Tree Air Freshener"))
    End Sub
End Class


Public Class LuxuryModel
    Inherits SedanModel

    Public Sub New()
        MyBase.New()
        Features.Add(New Feature(Me, "Leather Seats"))
        Features.Add(New Feature(Me, "Sunroof"))
    End Sub
End Class

Answer 1

如果您想保留当前的层次结构/属性，只需创建一个基类的实例，然后从派生类中的特性中减去基类中的特性。

或者，您可能需要考虑稍微更改您的类层次结构以使您自己更容易完成此操作。

例如，您可以将 Features 属性拆分为两个属性，比如 ModelFeatures 和 AllFeatures。

ModelFeatures 特定于当前模型(LuxuryModel 的“皮革座椅”和“天窗”等)。AllFeatures 返回 MyBase.AllFeatures 和 ModelFeatures 的联合。这使得获取当前模型的特征成为一种微不足道的属性访问。

附言请原谅我的 VB 错误，C# 是我的首选语言。