в 16:40, 26 мая 2010

2010-05-26T16:40:06Z

Admin: 1 версия

2010-05-26T12:45:00Z

1 версия

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==Define and fire event==

<source lang="vbnet">
Imports System
Public Class MainClass
Shared Dim WithEvents anEmployee As EmployeeWithEvents
Public Shared Sub Main()
anEmployee = New EmployeeWithEvents("Joe", 100000)
anEmployee.RaiseSalary(10)
End Sub
Shared Public Sub anEmployee_SalarySecurityEvent(ByVal Sender As EmployeeWithEvents, ByVal e As System.EventArgs) Handles anEmployee.SalarySecurityEvent
Console.WriteLine(Sender.Name & " had an improper salary raise attempted")
End Sub
End Class
Public Class EmployeeWithEvents
Public Name As String
Public Salary As Decimal
Public Event SalarySecurityEvent(ByVal Sender As EmployeeWithEvents,ByVal e As EventArgs)
Public Sub New(ByVal sName As String, ByVal curSalary As Decimal)
Name = sName
Salary = curSalary
End Sub
Public Overloads Sub RaiseSalary(ByVal Percent As Decimal)
RaiseEvent SalarySecurityEvent(Me, New System.EventArgs())
End Sub
End Class

</source>

==Use Delegate to react to an Event==

<source lang="vbnet">
Imports System
Imports System.Collections
Delegate Sub NameChangedDelegate(ByVal new_name As String)
Public Class MainClass

Shared Sub Main(ByVal args As String())
Dim student As New Student
AddHandler student.NameChanged, AddressOf Student_NameChanged
AddHandler student.NameChanged, AddressOf Student_NameChanged
student.FirstName = "First Name"
RemoveHandler student.NameChanged, AddressOf Student_NameChanged
student.LastName = "Last Name"
RemoveHandler student.NameChanged, AddressOf Student_NameChanged
End Sub
Private WithEvents student As Student
Shared Private Sub Student_NameChanged(ByVal new_name As String) Handles student.NameChanged
Console.WriteLine("Student_NameChanged: " & new_name)
End Sub

End Class

Public Class Student
" The FirstName property.
Private m_FirstName As String
Public Property FirstName() As String
Get
Return m_FirstName
End Get
Set(ByVal value As String)
m_FirstName = value
RaiseEvent NameChanged(m_FirstName & " " & m_LastName)
End Set
End Property
" The LastName property.
Private m_LastName As String
Public Property LastName() As String
Get
Return m_LastName
End Get
Set(ByVal value As String)
m_LastName = value
RaiseEvent NameChanged(m_FirstName & " " & m_LastName)
End Set
End Property
" List to hold the event handler delegates.
Private m_EventDelegates As New ArrayList
" Defines the event handler signature.
Public Delegate Sub NameChangedDelegate(ByVal new_name As String)
" Define the custom NameChanged event.
Public Custom Event NameChanged As NameChangedDelegate
AddHandler(ByVal value As NameChangedDelegate)
Console.WriteLine("AddHandler")
m_EventDelegates.Add(value)
End AddHandler
RemoveHandler(ByVal value As NameChangedDelegate)
Console.WriteLine("RemoveHandler")
m_EventDelegates.Remove(value)
End RemoveHandler
RaiseEvent(ByVal new_name As String)
Console.WriteLine("RaiseEvent (" & new_name & ")")
For Each a_delegate As NameChangedDelegate In m_EventDelegates
a_delegate(new_name.Replace(" ", "+"))
Next a_delegate
End RaiseEvent
End Event
End Class

</source>

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в 16:40, 26 мая 2010

Admin: 1 версия