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.Cry
End Sub