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<div align=center class=H1> <font color="#FFFFFF">VB.Net中文教程(13) Whole-Part关系(3)</font> </font> </font></div>
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<p align="left"> <font color="#000000">size = s<br>
End Sub<br>
End Class<br>
<br>
Private dr As Door<br>
Private win As Window<br>
Public Sub New()<br>
dr = New Door(50)<br>
win = New Window(100)<br>
End Sub<br>
Public Sub Show()<br>
Messagebox.Show("Door: " + str(dr.size) +
" Win: " + str(win.size))<br>
End Sub<br>
End Class<br>
'---------------------------------------------------------------------------------------------------<br>
Public Class Form1<br>
Inherits System.WinForms.Form<br>
<br>
Public Sub New()<br>
MyBase.New()<br>
Form1 = Me<br>
'This call is required by the Win Form Designer.<br>
InitializeComponent()<br>
'TODO: Add any initialization after the InitializeComponent()
call<br>
End Sub<br>
'Form overrides dispose to clean up the component list.<br>
Public Overrides Sub Dispose()<br>
MyBase.Dispose()<br>
components.Dispose()<br>
End Sub<br>
#Region " Windows Form Designer generated code "<br>
......<br>
#End Region<br>
Protected Sub Form1_Click(ByVal sender As Object, ByVal<br>
e As System.EventArgs)<br>
Dim h As New House()<br>
h.Show()<br>
End Sub<br>
End Class<br>
<br>
以此程序输出如下﹕<br>
Door:
50 Win: 100<br>
<br>
<br>
House 之对象诞生后﹐立即诞生内含之Door对象和Window对象。例如﹐宣告指令──<br>
Dim h As New House()<br>
<br>
此时﹐h 对象诞生了﹐其内含之dr 和win对象亦诞生了。<br>
<br>
<br>
<br>
此h 通称为「组合对象」(Composite object)﹐而dr 和win 则称为「部分对象」(Component object)。这种关系具有一项特色﹕组合对象与部分对象的寿命应该是一致的。<br>
在逻辑(Logical)意义上，这House 结构中﹐门和窗随着房子而具有「生死与共」之亲蜜关系，也就是寿命一致。在计算机实体(Physical)表达时，House
之对象并不「真正」包含Door及Window之对象﹐只是利用两个参考指向它们。所以上图也可想象如下： <br>
</font></span> <br>
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