Delegate With Multiple Method Sample Code Explaination

Public Class Form1

    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click

        Dim C As New Calculate

        Label1.Text = C.ShowValue(10, 10, Calculate.Perform.Add)

    End Sub

End Class

Public Class Calculate

    Public Enum Perform

        Add = 0

        Subtract = 1

        Divide = 2

        Square = 3

    End Enum

    Private Delegate Function CalcDel(A As Integer, B As Integer) As Integer

    Dim L As New List(Of CalcDel)

    Public Function ShowValue(A As Integer, B As Integer, Action As Perform) As Integer

        Dim msdAdd As CalcDel = AddressOf Add

        Dim msdSub As CalcDel = AddressOf Subract

        Dim msdDiv As CalcDel = AddressOf Divide

        L.Add(msdAdd)

        L.Add(msdSub)

        L.Add(msdDiv)

        Return L(Action).Invoke(A, B)

        'If not Delegate, WE had write Multiple IF Condition to manage Same.

        'If Action = Perform.Add Then

        '    Return Add(A, B)

        'ElseIf Action = Perform.Subtract Then

        '    Return Subract(A, B)

        'ElseIf Action = Perform.Divide Then

        '    Return Divide(A, B)

        'ElseIf Action = Perform.Square Then

        '    Return Square(A, B)

        'End If

    End Function

    Private Function Add(A As Integer, B As Integer) As Integer

        Return A + B

    End Function

    Private Function Subract(A As Integer, B As Integer) As Integer

        Return A - B

    End Function

    Private Function Divide(A As Integer, B As Integer) As Integer

        Return A / B

    End Function

    Private Function Square(A As Integer, B As Integer) As Integer

        Return A * B

    End Function

End Class