Programming Microsoft Visual Basic .NET/Programming Microsoft Visual Basic .NET (Microsoft Press)(X08-78517)(2002).bin/setup/vbnet/06 interfaces and delegates/interfacesdemo/supportfunctions.vb

Text File | 2001-07-28 | 1.7 KB | 51 lines

Module SupportFunctions
    ' Raise to the 4th power.
    Function Power4(ByRef x As Double) As Double
        ' This is faster than x^4.
        x = x * x
        Power4 = x * x
    End Function

    ' Two overloaded Sum functions
    Overloads Function Sum(ByVal n1 As Long, ByVal n2 As Long) As Long
        Sum = n1 + n2
        Console.WriteLine("The integer version has been invoked.")
    End Function

    Overloads Function Sum(ByVal n1 As Single, ByVal n2 As Single) As Single
        Sum = n1 + n2
        Console.WriteLine("The floating point version has been invoked.")
    End Function

    ' Set an object to Nothing and clear its Dispose method if possible.
    Sub ClearObject(ByRef obj As Object)
        If TypeOf obj Is IDisposable Then
            ' You need an explicit case if Option Strict is On.
            CType(obj, IDisposable).Dispose()
        End If
        obj = Nothing
    End Sub

End Module

' This module is used to demonstrate that modules can raise events

Module FileOperations
    Event Notify_CopyFile(ByVal source As String, ByVal destination As String)
    Event Notify_DeleteFile(ByVal filename As String)

    Sub CopyFile(ByVal source As String, ByVal destination As String)
        ' Perform the file copy.
        System.IO.File.Copy(source, destination)
        ' Notify that a copy occurred.
        RaiseEvent Notify_CopyFile(source, destination)
    End Sub

    Sub DeleteFile(ByVal filename As String)
        ' Perform the file deletion.
        System.IO.File.Delete(filename)
        ' Notify that a deletion occurred.
        RaiseEvent Notify_DeleteFile(filename)
    End Sub
End Module