Multicasting in VB.NET

In this article we will discuss about the Multicasting functionality.
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Multicasting enables you to combine several handler methods in a list so that all of them are bound to the same delegate object. When Invoke is called on the delegate object, the MulticastDelegate class provides the code to execute each handler method in the list. 

Defining Multicasting:

In VB.NET taking the method for two different delegate object objects and combing them into a multicast delegate object.

Public Delegate Sub Bank() 
'Create two indiviual delegate

obj1, obj2 As Bank
    obj1 = AddressOf Account.Deposit
    obj2 = AddressOf Account.withdraw

'Combine deligate into multicast delegate

result As [Delegate] = [Delegate].Combine(obj1, obj2)
'Convert referance to banktype

handlers As Bank


  • The use of square bracket around the name of the [Delegate] class . These square bracket are required because deligate is also a key word in VB.NET they serve as escape characters telling the visual basic compiler that you indented to use delegate as class name and not a keyword  

  • The call to combine returns a reference to a newly created multicast deligate object. This conversion is required if you wants to call the invoke method.

Coding for Multicasting:

Module Module1
    Public Delegate Sub Bank()
    Public Class Account
        Public Sub Diposit() 
            Console.WriteLine("you are successfully Deposit"
        End Sub
    End Class
    Class Chal : Inherits Account   
        Public Sub Withdraw()
            Console.WriteLine("you are successfully withdraw")
        End Sub
    End Class
    Sub Main() 
        Dim obj As New Chal
        Dim obj1 As Bank
        Dim obj2 As Bank
        obj1 = New Bank(AddressOf obj.Diposit)
        obj2 = New Bank(AddressOf obj.Withdraw)
        Dim result As [Delegate] = [Delegate].Combine(obj1, obj2)
        Dim handlers As Bank
        handlers = CType(result, Bank)
    End Sub



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