How to Use Delegates in Vb.Net
In this article I will try to explain you the basics of Delegate in VB.Net.
A delegate is a type that safely encapsulates a method, similar to a function pointer in C and C++. Unlike C function pointers, delegates are object-oriented, type safe, and secure. The type of a delegate is defined by the name of the delegate. The following example declares a delegate named mydlg that can encapsulate a method :
How we use delegate in VB.net programming:
public delegate sub mydlg()
Then we use the delegate by simply declaring a variable of the delegate and assigning the sub or function to run when called. First the sub to be called:
Private Sub message()
Console.WriteLine ( "show message" )
End Sub
now it matches our declaration of MyDlg. it's a sub routine with no parameters. And then our test code:
Dim dlg As mydel
dlg = New mydel(AddressOf message)
dlg.Invoke()
When we invoke the delegate, the message sub is run.
The following code define the delegate:
Module Module1
Public Delegate Sub mydel()
Public Delegate Sub mydel1(ByVal a As Integer)
Public Sub message()
Console.WriteLine("show message")
End Sub
Public Sub add(ByVal a As Integer)
Dim b As Integer
b = a + a
Console.Write(" Addition is : ")
Console.WriteLine(b)
End Sub
Sub Main()
Dim dlg As mydel
dlg = New mydel(AddressOf message)
dlg.Invoke()
Dim dlg1 As mydel1
dlg1 = New mydel1(AddressOf add)
dlg1.Invoke(10)
End Sub
End Module
OUTPUT:
Conclusion:
Hope this article would have helped you in understanding Delegates in VB.NET.