Question

三个问题：

这种使用事件的方式是否正确？
我无法理解使用WithEvents我在一些例子中看到人们正在使用它可以根据我的例子或者何时使用它来解释。
是否可以不创建此案例：

Dim Subscrib1 As New Policeman（carStart）

我的意思是我想要有一个我不需要创建实例的课程，例如让我们参加警察课程，我是否真的需要创建他的实例并将carStart传递给它以接收事件？例如，让我们想象警察类包含方法Do和在Console.writeline内部（＆＃34; doSomething＆＃34;）。我希望在引发somwhere carStart.Drive时执行此方法。

Module Module1

    Sub Main()

        Dim carStart As New Driver(122)
        Dim Subscrib1 As New Passenger(carStart)
        Dim Subscrib2 As New PoliceControl(carStart)

        carStart.StartToDrive()
        carStart.CheckCurrentSpeed()

        Console.ReadLine()
    End Sub

    Class Driver
        Public Delegate Sub DoIt()
        Public Event Drive As DoIt
        Public Event CurrentSpeed()

        Public SpeedDrive As Integer

        Public Sub New(ByVal speed As Integer)
            Me.SpeedDrive = speed
        End Sub

        Public Sub StartToDrive()
            Console.WriteLine("I am driving")
            RaiseEvent Drive()
        End Sub

        Public Sub CheckCurrentSpeed()
            Console.WriteLine("Current speed is " & SpeedDrive)
            RaiseEvent CurrentSpeed()
        End Sub

    End Class

    Class Passenger
        Sub New(classWithevent As Driver)
            If classWithevent.SpeedDrive = 0 Then
                AddHandler classWithevent.Drive, AddressOf TakePassanger
            Else
                RemoveHandler classWithevent.Drive, AddressOf TakePassanger
            End If
        End Sub

        Public Sub TakePassanger()
            Console.WriteLine("Taking passenger")
        End Sub
    End Class

    Class PoliceControl
        Sub New(classWithevent As Driver)
            If classWithevent.SpeedDrive > 120 Then
                AddHandler classWithevent.CurrentSpeed, AddressOf PolicemanCheckTheCarSpeed
            Else
                RemoveHandler classWithevent.CurrentSpeed, AddressOf PolicemanCheckTheCarSpeed
            End If
        End Sub

        Public Sub PolicemanCheckTheCarSpeed()
            Console.WriteLine("Stop for control")
        End Sub
    End Class

End Module

事件提供者和订阅者正确的使用方式

0 个答案: