难道possable在vb.net中有这种构造的任何派生类对象中的低音类中的方法？ 在这种code x.Clone应返回Bar对象。 是dulpicate的code在这两个类的与两个不同的对象类型的唯一方法。

 模块模块1

    副主（）
        昏暗x As中新的吧
        昏暗ÿ，酒吧= x.Clone
    结束小组

前端模块

公共类Foo
    实现ICloneable
    公共功能的clone（）为对象实现System.ICloneable.Clone
        克隆= Me.new（）编译失败不会在构造函数
        克隆=新富'建在派生类的新富
    端功能
末级

公共类酒吧
    继承富
    额外的实施
    但没有加入域
末级
 

解决方案

答案取决于你所要完成的克隆方法具体是什么。

如果你想创建当前类的新实例，而无需实际复制任何属性（这是听起来像你可能有兴趣根据样本code和描述那样），那么简单的解决方案是

 公共类Foo
    实现ICloneable

    公共功能的clone（）为对象实现System.ICloneable.Clone
        返回Activator.CreateInstance（Me.GetType）
    端功能
末级
 

您可以测试这种被称为在酒吧添加消息（或某种调试或输出）：

 公共类酒吧
    继承富

    公共子新（）
        MSGBOX（测试）
    结束小组

末级
 

如果你有选项严，我强烈建议，在code的主要是：

 子的Main（）
    昏暗x As中新的吧
    昏暗ÿ，酒吧= DirectCast（x.Clone，酒吧）
结束小组
 

不过，如果您有兴趣从当前类复制成员的值，可以使用的 MemberwiseClone ：

 公共类Foo
    实现ICloneable

    公共功能的clone（）为对象实现System.ICloneable.Clone
        返回Me.MemberwiseClone
    端功能
末级
 

然而，这只会造成一个浅拷贝，将复制引用，并不会调用上栏的构造。当我们使用MemberwiseClone以这种方式，我们总是加可重写方法，可以通过继承用于执行克隆后清理：

 公共类Foo
    实现ICloneable

    公共功能的clone（）为对象实现System.ICloneable.Clone
        昏暗oObject作为富

        oObject = DirectCast（Me.MemberwiseClone，富）
        oObject.PostCloneCleanup（）

        返回oObject
    端功能

    受保护的可重写小组PostCloneCleanup（）

    结束小组
末级

公共类酒吧
    继承富

    公共子新（）
        MSGBOX（测试）
    结束小组

    受保护的覆盖子PostCloneCleanup（）
        MSGBOX（PostCloneCleanup）
    结束小组

末级
 

序列化和反序列化使用BinaryFormmater：

最后，如果浅复制或处理复制引用是不是你喜欢，你可以使用一个便宜，但非常有效的一招进行深拷贝

 公共功能CreateDeepCopy（Of T）中（BYVAL oRecord为t）为t

    如果oRecord是没有那么
        返回任何结果
    结束如果

    如果不oRecord.GetType.IsSerializable然后
        抛出新的ArgumentException（oRecord.GetType.ToString＆安培;是不是可序列化）
    结束如果

    昏暗oFormatter作为新System.Runtime.Serialization.Formatters.Binary.BinaryFormatter

    使用ostream的作为IO.MemoryStream =新IO.MemoryStream
        oFormatter.Serialize（ostream的，oRecord）
        oStream.Position = 0
        返回DirectCast（oFormatter.Deserialize（ostream的），T）
    结束使用
端功能
 

这要求类可序列化，但是这是很容易做到的。

Is it possable in vb.net to have a method that constructs an object of any derived class in the bass class? In this code x.Clone should return a Bar object. Is the only way to dulpicate the code in both class's with both different object types.

Module Module1

    Sub Main()
        Dim x As New Bar
        Dim y As Bar = x.Clone
    End Sub

End Module

Public Class Foo
    Implements ICloneable
    Public Function Clone() As Object Implements System.ICloneable.Clone
        Clone = Me.new() 'fails to compile as not in a constructor
        Clone = new Foo 'constructs a new foo in the derived class
    End Function
End Class

Public Class Bar
    Inherits Foo
    'additional implementation
    'but no addition fields
End Class

The answer depends on specifically what you are trying to accomplish in the cloning method.

If you want to create a new instance of the current class without actually copying any of the properties (which is sounds like you may be interested in doing based on the sample code and description), then the simple solution is:

Public Class Foo
    Implements ICloneable

    Public Function Clone() As Object Implements System.ICloneable.Clone
        Return Activator.CreateInstance(Me.GetType)
    End Function
End Class

You can test that this is called by adding a message (or some sort of debug or output) in Bar:

Public Class Bar
    Inherits Foo

    Public Sub New()
        MsgBox("Test")
    End Sub

End Class

If you have Option Strict On, which I strongly recommend, the code in main would be:

Sub Main()
    Dim x As New Bar
    Dim y As Bar = DirectCast(x.Clone, Bar)
End Sub

However, if you are interested in copying the member values from the current class, you can use MemberwiseClone:

Public Class Foo
    Implements ICloneable

    Public Function Clone() As Object Implements System.ICloneable.Clone
        Return Me.MemberwiseClone
    End Function
End Class

However, this will only create a shallow copy, will copy references, and will not invoke the constructor on Bar. When we use MemberwiseClone in this manner, we always add an overridable method that can be used by inheritors to perform post-clone cleanup:

Public Class Foo
    Implements ICloneable

    Public Function Clone() As Object Implements System.ICloneable.Clone
        Dim oObject As Foo

        oObject = DirectCast(Me.MemberwiseClone, Foo)
        oObject.PostCloneCleanup()

        Return oObject
    End Function

    Protected Overridable Sub PostCloneCleanup()

    End Sub
End Class

Public Class Bar
    Inherits Foo

    Public Sub New()
        MsgBox("Test")
    End Sub

    Protected Overrides Sub PostCloneCleanup()
        MsgBox("PostCloneCleanup")
    End Sub

End Class

Finally, if shallow copying or dealing with copied references is not to you liking, you can perform a deep copy using a cheap, but very effective trick: serialization and deserialization using the BinaryFormmater:

Public Function CreateDeepCopy(Of T)(ByVal oRecord As T) As T

    If oRecord Is Nothing Then
        Return Nothing
    End If

    If Not oRecord.GetType.IsSerializable Then
        Throw New ArgumentException(oRecord.GetType.ToString & " is not serializable")
    End If

    Dim oFormatter As New System.Runtime.Serialization.Formatters.Binary.BinaryFormatter

    Using oStream As IO.MemoryStream = New IO.MemoryStream
        oFormatter.Serialize(oStream, oRecord)
        oStream.Position = 0
        Return DirectCast(oFormatter.Deserialize(oStream), T)
    End Using
End Function

This requires that the classes be serializable, but that is easy to do.