例子演示下VB实现多态

在工程中创建3个Class Module，名字分别为：Animal、Cat、Dog：

Animal是接口：Sub Cry()

End Sub

Cat和Dog类是实现：

Implements Animal

Private Sub Animal_Cry()    MsgBox "miao miao"End Sub

Implements Animal

Private Sub Animal_Cry()    MsgBox "wang wang"End Sub

然后调用的代码如下：Private Sub Command1_Click()    Dim a1 As Animal    Dim a2 As Animal        Set a1 = New Dog    Set a2 = New Cat        a1.Cry    a2.CryEnd Sub