You can override some of the built-in VB keywords with your own version of the function. For instance, FileDateTime is a handy built-in function in VB, but it suffers from one big problem: It cant set the date/time of a file. By overriding the built-in function, however, you can provide this feature. With this approach, the function can determine for itself how it is being used and perform accordingly.
You can override a number of keywords and functions in this manner:
Private Declare Function SystemTimeToFileTime Lib _ "kernel32" (lpSystemTime As SYSTEMTIME, _ lpFileTime As FILETIME) As LongPrivate Declare Function LocalFileTimeToFileTime _ Lib "kernel32" (lpLocalFileTime As FILETIME, _ lpFileTime As FILETIME) As LongPrivate Declare Function CreateFile Lib "kernel32" _ Alias "CreateFileA" (ByVal lpFileName As _ String, ByVal dwDesiredAccess As Long, ByVal _ dwShareMode As Long, lpSecurityAttributes As _ Any, ByVal dwCreationDisposition As Long, _ ByVal dwFlagsAndAttributes As Long, _ ByVal hTemplateFile As Long) As LongPrivate Declare Function SetFileTime Lib "kernel32" _ (ByVal hFile As Long, lpCreationTime As Any, _ lpLastAccessTime As Any, lpLastWriteTime As _ Any) As LongPrivate Declare Function CloseHandle Lib "kernel32" _ (ByVal hObject As Long) As LongPrivate Type FILETIME dwLowDateTime As Long dwHighDateTime As LongEnd TypePrivate Type SYSTEMTIME wYear As Integer wMonth As Integer wDayOfWeek As Integer wDay As Integer wHour As Integer wMinute As Integer wSecond As Integer wMilliseconds As IntegerEnd TypePrivate Const GENERIC_WRITE As Long = &H40000000Private Const FILE_SHARE_READ As Long = &H1Private Const FILE_SHARE_WRITE As Long = &H2Private Const OPEN_EXISTING As Long = 3Public Function FileDateTime(ByVal FileName As String, _ Optional ByVal TimeStamp As Variant) As Date ' Raises an error if one occurs just like FileDateTime Dim x As Long Dim Handle As Long Dim System_Time As SYSTEMTIME Dim File_Time As FILETIME Dim Local_Time As FILETIME If IsMissing(TimeStamp) Then 'It's missing so they must want to GET the timestamp 'This acts EXACTLY like the original built-in function FileDateTime = VBA.FileDateTime(FileName) ElseIf VarType(TimeStamp) <> vbDate Then 'You must pass in a date to be valid Err.Raise 450 Else System_Time.wYear = Year(TimeStamp) System_Time.wMonth = Month(TimeStamp) System_Time.wDay = Day(TimeStamp) System_Time.wDayOfWeek = _ Weekday(TimeStamp) - 1 System_Time.wHour = Hour(TimeStamp) System_Time.wMinute = Minute(TimeStamp) System_Time.wSecond = Second(TimeStamp) System_Time.wMilliseconds = 0 'Convert the system time to a file time x = SystemTimeToFileTime(System_Time, Local_Time) 'Convert local file time to file time based on UTC x = LocalFileTimeToFileTime(Local_Time, File_Time) 'Open the file so we can get a file handle to 'the file Handle = CreateFile(FileName, GENERIC_WRITE, _ FILE_SHARE_READ Or FILE_SHARE_WRITE, _ ByVal 0&, OPEN_EXISTING, 0, 0) If Handle = 0 Then Err.Raise 53, "FileDateTime", _ "Can't open the file" Else 'Now change the file time and date stamp x = SetFileTime(Handle, ByVal 0&, _ ByVal 0&, File_Time) If x = 0 Then 'Error occured Err.Raise 1, "FileDateTime", _ "Unable to set file timestamp" End If Call CloseHandle(Handle) 'Return newly set date/time FileDateTime = VBA.FileDateTime(FileName) End If End IfEnd Function
