Question

假设我有一个通用接口（VB.NET）：

Public Interface IBase(Of T As {IBase(Of T)})
    Property Parent() As T

我有两个实现接口的类

Public Class Derive1
    Implements IBase(Of Derive1)
    Public Property Parent() As Derive1 Implements IBase(Of Derive1).Parent

Public Class Derive2
    Implements IBase(Of Derive2)
    Public Property Parent() As Derive2 Implements IBase(Of Derive2).Parent

如何使用可以接受Derive1和Derive2的通用List，以便：

genList.Add(Derive1)
genList.Add(Derive2)

Answer 1

让Derive1和Derive2实现一个通用接口，然后创建该接口的List。例如，假设您要迭代通用列表并拥有一个可以在该列表中的Derive1和Derive2对象上执行的方法（如CountChildren）。首先，您需要创建一个界面，如下所示：

Public Interface ICalculations
    Function CountChildren() As Integer
End Interface

然后，您将要设置Derive1和Derive2，以便它们实现此接口。这可能是这样的：

Public Class Derive1
    Implements IBasicPortfolio(Of Derive1)
    Implements ICalculations
    Public Property Value() As Integer
        Get
            Return m_Value
        End Get
        Set
            m_Value = Value
        End Set
    End Property
    Private m_Value As Integer
    Public Property [Next]() As Derive1
        Get
            Return m_Next
        End Get
        Set
            m_Next = Value
        End Set
    End Property
    Private m_Next As Derive1
    Public Function CountChildren() As Integer
        Return 1 + [Next].CountChildren()
    End Function
End Class

Public Class Derive2
    Implements IBasicPortfolio(Of Derive2)
    Implements ICalculations
    Public Property Value() As Integer
        Get
            Return m_Value
        End Get
        Set
            m_Value = Value
        End Set
    End Property
    Private m_Value As Integer
    Public Property [Next]() As Derive1
        Get
            Return m_Next
        End Get
        Set
            m_Next = Value
        End Set
    End Property
    Private m_Next As Derive1
    Public Function CountChildren() As Integer
        Return 1 + [Next].CountChildren()
    End Function
End Class

然后你可以创建一个ICalculations列表，它可以包含Derive1和Derive2对象：

Dim foo = New List(Of ICalculations)()

foo.Add(New Derive1())
foo.Add(New Derive2())

For Each bar As var In foo
    bar.CountChildren()
Next

如何使用通用列表来获取实现公共接口的派生类

1 个答案: