address of 顧名思義，就是地址指向，每個(gè)函數(shù)都有一個(gè)地址，address of后面加函數(shù)名稱。
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handels 事件，你看看按鈕的單擊事件，窗體的啟動(dòng)事件，每個(gè)后面都有這個(gè)。
delegate 就是聲明一個(gè)委托了。
我也不好詳細(xì)說，其實(shí)你上Baidu搜這幾個(gè)關(guān)鍵字加上點(diǎn)注解，比如“delegate的用法”，N多！
一委托：此示例演示如何將方法與委托關(guān)聯(lián)然后通過委托調(diào)用該方法。
創(chuàng)建委托和匹配過程
創(chuàng)建一個(gè)名為 MySubDelegate 的委托。
Delegate Sub MySubDelegate(ByVal x As Integer)
聲明一個(gè)類，該類包含與該委托具有相同簽名的方法。
Class class1
Sub Sub1(ByVal x As Integer)
MsgBox("The value of x is: " CStr(x))
End Sub
End Class
定義一個(gè)方法，該方法創(chuàng)建該委托的實(shí)例并通過調(diào)用內(nèi)置的 Invoke 方法調(diào)用與該委托關(guān)聯(lián)的方法。
Protected Sub DelegateTest()
Dim c1 As New class1
' Create an instance of the delegate.
Dim msd As MySubDelegate = AddressOf c1.Sub1
' Call the method.
msd.Invoke(10)
End Sub
二、事件
下面的示例程序闡釋如何在一個(gè)類中引發(fā)一個(gè)事件，然后在另一個(gè)類中處理該事件。AlarmClock 類定義公共事件 Alarm，并提供引發(fā)該事件的方法。AlarmEventArgs 類派生自 EventArgs，并定義 Alarm 事件特定的數(shù)據(jù)。WakeMeUp 類定義處理 Alarm 事件的 AlarmRang 方法。AlarmDriver 類一起使用類，將使用 WakeMeUp 的 AlarmRang 方法設(shè)置為處理 AlarmClock 的 Alarm 事件。
該示例程序使用事件和委托和引發(fā)事件中詳細(xì)說明的概念。
示例
' EventSample.vb.
'
Option Explicit
Option Strict
Imports System
Imports System.ComponentModel
Imports Microsoft.VisualBasic
Namespace EventSample
' Class that contains the data for
' the alarm event. Derives from System.EventArgs.
'
Public Class AlarmEventArgs
Inherits EventArgs
Private _snoozePressed As Boolean
Private nrings As Integer
'Constructor.
'
Public Sub New(snoozePressed As Boolean, nrings As Integer)
Me._snoozePressed = snoozePressed
Me.nrings = nrings
End Sub
' The NumRings property returns the number of rings
' that the alarm clock has sounded when the alarm event
' is generated.
'
Public ReadOnly Property NumRings() As Integer
Get
Return nrings
End Get
End Property
' The SnoozePressed property indicates whether the snooze
' button is pressed on the alarm when the alarm event is generated.
'
Public ReadOnly Property SnoozePressed() As Boolean
Get
Return _snoozePressed
End Get
End Property
' The AlarmText property that contains the wake-up message.
'
Public ReadOnly Property AlarmText() As String
Get
If _snoozePressed Then
Return "Wake Up!!! Snooze time is over."
Else
Return "Wake Up!"
End If
End Get
End Property
End Class
' Delegate declaration.
'
Public Delegate Sub AlarmEventHandler(sender As Object, _
e As AlarmEventArgs)
' The Alarm class that raises the alarm event.
'
Public Class AlarmClock
Private _snoozePressed As Boolean = False
Private nrings As Integer = 0
Private stopFlag As Boolean = False
' The Stop property indicates whether the
' alarm should be turned off.
'
Public Property [Stop]() As Boolean
Get
Return stopFlag
End Get
Set
stopFlag = value
End Set
End Property
' The SnoozePressed property indicates whether the snooze
' button is pressed on the alarm when the alarm event is generated.
'
Public Property SnoozePressed() As Boolean
Get
Return _snoozePressed
End Get
Set
_snoozePressed = value
End Set
End Property
' The event member that is of type AlarmEventHandler.
'
Public Event Alarm As AlarmEventHandler
' The protected OnAlarm method raises the event by invoking
' the delegates. The sender is always this, the current instance
' of the class.
'
Protected Overridable Sub OnAlarm(e As AlarmEventArgs)
RaiseEvent Alarm(Me, e)
End Sub
' This alarm clock does not have
' a user interface.
' To simulate the alarm mechanism it has a loop
' that raises the alarm event at every iteration
' with a time delay of 300 milliseconds,
' if snooze is not pressed. If snooze is pressed,
' the time delay is 1000 milliseconds.
'
Public Sub Start()
Do
nrings += 1
If stopFlag Then
Exit Do
Else
If _snoozePressed Then
System.Threading.Thread.Sleep(1000)
If (True) Then
Dim e As New AlarmEventArgs(_snoozePressed, nrings)
OnAlarm(e)
End If
Else
System.Threading.Thread.Sleep(300)
Dim e As New AlarmEventArgs(_snoozePressed, nrings)
OnAlarm(e)
End If
End If
Loop
End Sub
End Class
' The WakeMeUp class has a method AlarmRang that handles the
' alarm event.
'
Public Class WakeMeUp
Public Sub AlarmRang(sender As Object, e As AlarmEventArgs)
Console.WriteLine((e.AlarmText + ControlChars.Cr))
If Not e.SnoozePressed Then
If e.NumRings Mod 10 = 0 Then
Console.WriteLine(" Let alarm ring? Enter Y")
Console.WriteLine(" Press Snooze? Enter N")
Console.WriteLine(" Stop Alarm? Enter Q")
Dim input As String = Console.ReadLine()
If input.Equals("Y") Or input.Equals("y") Then
Return
Else
If input.Equals("N") Or input.Equals("n") Then
CType(sender, AlarmClock).SnoozePressed = True
Return
Else
CType(sender, AlarmClock).Stop = True
Return
End If
End If
End If
Else
Console.WriteLine(" Let alarm ring? Enter Y")
Console.WriteLine(" Stop Alarm? Enter Q")
Dim input As String = Console.ReadLine()
If input.Equals("Y") Or input.Equals("y") Then
Return
Else
CType(sender, AlarmClock).Stop = True
Return
End If
End If
End Sub
End Class
' The driver class that hooks up the event handling method of
' WakeMeUp to the alarm event of an Alarm object using a delegate.
' In a forms-based application, the driver class is the
' form.
'
Public Class AlarmDriver
Public Shared Sub Main()
' Instantiates the event receiver.
Dim w As New WakeMeUp()
' Instantiates the event source.
Dim clock As New AlarmClock()
' Wires the AlarmRang method to the Alarm event.
AddHandler clock.Alarm, AddressOf w.AlarmRang
clock.Start()
End Sub
End Class
End Namespace
1、是的，作用域的區(qū)別如下：
Public 公有成員，表示所有模塊的所有其它過程都可訪問這個(gè)成員。
Private
私有成員，表示只在其類的塊中，唯有友元（Friend）才可以訪問，屬私有對(duì)象。其他地方均不可以訪問。
Protected 半私有成員，表示只在其類的塊中，或者是派生類中，友元才能訪問。
Friend
友元，設(shè)置成友元的情況下下，可以不受public跟private的約束，可以進(jìn)行私有成員的訪問。
所以兩個(gè)不同的模塊中唯有 Public 是可以互相訪問的。
2、能觸發(fā)。
Private 是相對(duì)于其他類來講是 Private 的，對(duì)于 C1 本身是可以訪問的。既然 class2 是 C2 的實(shí)例，并繼承了 C1，那么是可以觸發(fā) C1 中的 Private 過程的。
可以在選定全部子節(jié)點(diǎn)前，發(fā)送一個(gè)變量給全部子節(jié)點(diǎn)（有個(gè)tag屬性可以利用），告訴它們不應(yīng)該執(zhí)行某事件（if語句）。
委托是可用于調(diào)用其他對(duì)象方法的對(duì)象。它們有時(shí)被稱為類型安全函數(shù)指針，因?yàn)樗鼈兣c其他編程語言中所使用的函數(shù)指針相似。但不同于函數(shù)指針，Visual Basic .NET 委托是基于 System.Delegate 類的引用類型，它可以引用共享方法 —無需特定的類實(shí)例即可調(diào)用的方法和實(shí)例方法。
委托在調(diào)用過程和被調(diào)用過程需要媒介的情況下是很有用的。例如，您可能想讓一個(gè)引發(fā)事件的對(duì)象能夠在不同的環(huán)境下調(diào)用不同的事件處理程序。不幸的是，引發(fā)事件的對(duì)象無法提前知道處理特定事件的事件處理程序。Visual Basic .NET 通過在使用 AddHandler 語句時(shí)創(chuàng)建委托，可讓您動(dòng)態(tài)地將事件處理程序與事件關(guān)聯(lián)。在運(yùn)行時(shí)，委托將各種調(diào)用轉(zhuǎn)發(fā)到相應(yīng)的事件處理程序。
盡管可以創(chuàng)建自己的委托，但在大多數(shù)情況下，Visual Basic .NET 為您創(chuàng)建委托并提供具體信息。例如，Event 語句將名為 EventNameEventHandler 的委托類隱式定義為 Event 語句所在類的嵌套類，且其簽字與該事件相同。AddressOf 語句則隱式創(chuàng)建委托的實(shí)例。例如，以下兩行代碼是等效的：
AddHandler Button1.Click, AddressOf Me.Button1_Click
' AddHandler 指向引發(fā)事件的對(duì)象，AddressOf則確定該事件對(duì)象所要調(diào)用的事件處理程序
'上述行為又可以稱為 監(jiān) 視
AddHandler Button1.Click, New EventHandler(AddressOf Button1_Click)。
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