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It is now just two days left to nominate IBM Champions. So if you know someone who have been helping the community, perhaps through video tutorials, blogs, presenting at (or organizing) conferences or answering questions on different forums, submit a nomination.

This is how IBM explains what a Champion is:

An IBM Champion is someone who makes exceptional contributions to the technical community. Contributions can come in a variety of forms, and popular contributions include blogging, speaking at conferences or events, moderating forums, leading user groups, and authoring books or magazines.

So hurry up. There are many worthy champions out there!

Swedish Air Force JAS39 Gripen (single seat variant).
Photo by Ernst Vikne (Creative Commons BY-SA).

According to an article in Aviation Week, Boeing is planning to team up with Swedish airplane manufacturer Saab to offer a new two-seater training version of the JAS 39 Gripen fighter to the US Air Force. The old Northrop T-38 is being retired, and a new trainer is needed in the future.
Approximate 350 trainers are needed, but in addition the fighter could be useful for aggressor training (e.g Red Flag and Top Gun), currently flying mostly F-15 and F-16 fighters.

Another use for the two-seater JAS 39F model would be as a companion trainer for the F-22 Raptor and F-35 Joint Strike Fighter, neither of which are being produced in a two-seat version. Currently T-38 is used in this position as well.

A source in the USAF quoted in the Aviation Week article hints that the step is not very far to use an affordable air defense fighter to replace the aging Air National Guard F-15/F-16 fighters.

Hungarian Air Force Saab JAS39D Gripen

JAS 39 have been produced in four different variants. JAS 39A and B were the initial version that entered service in 1996. Some of them have been updated to the new C/D models, and additional JAS 39C/D have been delivered to countries like Hungary, South Africa, Thailand and Czech Republic.

Switzerland is intending to buy the new JAS 39E single-seat model, after a referendum in 2014. Sweden is also planing to upgrade to that model when it becomes available.

The F model Boeing is intending to offer the US Air Force is a brand new development, possibly with some functionality not needed in a trainer removed to save cost.

I am back after a short break. Let’s continue where we left off. Today I will talk about object oriented Lotusscript. We looked at functions in part 3 of this series, and while functions are very useful, you should consider building objects instead.

So why would you use classes? The short answer is that they are much more powerful and also much easier to maintain. The code is usually shorter and I get a better overview. It is modular and can easily be moved to other applications. It is easy to maintain and add functionality. And the calling code can be very compact and easy to understand as well.

You are already using objects/classes today, when you are writing Lotusscript code. The DOM (Domino Object Model) are made up of classes that let you access different Domino objects, like sessions, databases, views, documents, etc. You already know how to call and use classes, now we will look at creating your own. It is much easier than you probably think.

About 2 years ago, I wrote two articles about object oriented Lotusscript, but the code samples were scrambled when I moved my blog to WordPress. You can find the old articles here and here. But the article you are currently reading will be look at a more basic class, and explain more of the code.

I have posted several classes here on my blog in the past, doing different things:
Get latitude and longitude for an address – Win32 only
Mail Merge/Form Letters in Lotusscript
Mail Notification Class
Class for File Functions
HTML Retrieval Class – Win32 only
Accessing Windows Clipboard – Win32 only

Take a look at those article and you should get an understanding of how to write a class..

Your First Class

Let’s start with a very simple class. It will contain some math functions. We will start with just one, used to add two values together.

Option Public
Option Declare

Class MathClass
    Public value1 As Integer
    Public value2 As Integer

    %REM
        Sub New()
        Description: Constructor for the class
    %END REM
    Public Sub New()
        '*** We will add code here later
    End Sub

    %REM
        Function Add()
        Description: Adding value1 and value2 and retur result
    %END REM
    Public Function Add() As Integer
        Add = value1 + value2
        End Function
End Class

And this is how you use the class:

Sub Initialize
    Dim math As MathClass
    '*** Create new instance of MathClass
    Set math = New MathClass()
    '*** Set the two values in the class
    math.value1 = 4
    math.value2 = 6
    '*** Display the result of the Add() function
    MsgBox math.Add()
End Sub

Easy, wasn’t it? However, we can expand a little on this. Instead of assigning the variables value1 and value2 after the math object is created, we can pass the values to the object at create time:

Option Public
Option Declare

Class MathClass
    Public value1 As Integer
    Public value2 As Integer

    %REM
        Sub New()
        Description: Constructor for the class, taking two integers as arguments
    %END REM
    Public Sub New(arg1 As Integer, arg2 As Integer)
        value1 = arg1
        value2 = arg2
    End Sub

    %REM
        Function Add()
        Description: Adding value1 and value2 and return result
    %END REM
    Public Function Add() As Integer
        Add = value1 + value2
    End Function
End Class

And here is the updated code to use the class:

Sub Initialize
    Dim math As MathClass
    '*** Create new instance of MathClass
    Set math = New MathClass(4,6)
    '*** Display the result of the Add() function
    MsgBox math.Add()
End Sub

We can now easily add more functions to the class, for subtraction, multiplication, etc.

Get/Set properties of your class

Often it is a good idea to check the values you pass to the class. The easiest way is to use the Set properties. You use the corresponding Get property to read values from the class. In this example, we will check if the value is greater than 100, and if so we will reduce the value by 100 before storing it in the rivate variable used inside the class.

Option Public
Option Declare

Class MathClass
    Private p_value1 As Integer
    Private p_value2 As Integer

    %REM
        Sub New()
        Description: Constructor for the class
    %END REM
    Public Sub New()

    End Sub

    %REM
        Property Set value1
        Description: Set value1 and subtract 100 if needed
    %END REM
    Property Set value1 
        If value1>100 Then
            p_value1 = value1 - 100
        Else    
            p_value1 = value1
        End If
    End Property

    %REM
        Property Set value2
        Description: Set value2 and subtract 100 if needed
    %END REM
    Property Set value2 
        If value2>100 Then
            p_value2 = value2 - 100
        Else    
            p_value2 = value2
        End If
    End Property

    %REM
        Function Add()
        Description: Adding value1 and value2 and return result
    %END REM
    Public Function Add() As Integer
        Add = p_value1 + p_value2
    End Function
End Class

We call the class exactly like in our first example. But remember that we reduce the number by 100 if it is larger than 100. The output of this code is identical to the previous examples:

Sub Initialize
    Dim math As MathClass

    '*** Create new instance of MathClass
    Set math = New MathClass()
    '*** Set properties of the object
    math.value1 = 4
    math.value2 = 106
    '*** Display the result of the Add() function
    MsgBox math.Add()
End Sub

Let’s say we want to add a function that subtract the first value from the second value. We then just add a Subtract() function to the class:

    %REM
        Function Subtract()
        Description: Subtracting value1 from value2 and return result
    %END REM
    Public Function Subtract() As Integer
        Subtract = p_value2 - p_value1
    End Function

Now you have the foundation of object oriented Lotusscript. Go forth and conquer!

You can now download the pocket agenda for Connect 2013 from the conference website. I always found this one of the best planning tools for the conference, together with the session database of course.

So if you haven’t downloaded and printed a copy, get it here.

In the developerWorks forum for Notes 8, a user asked about how to check if a file (in this particular instance attached to a Rich Text Lite field) is an Adobe PDF file. The easiest (but of course not fool proof) way is to simply check the extension of the file name.

That reminded me that I have a simple Lotusscript class with some file functions that would simplify the parsing of a filename, if you want to get the path, the file name or just the extension. I thought that perhaps more people could use this, so I am posting it below. Thanks to Andre Guirard for the code to create directories. That is a function I sometimes need when working with files, so I added that to the class for my convenience.

Option Public
Option Declare

Class FileObject
  Private p_FileName As String
  Private p_FilePath As String
  Private p_Extension As String

  Public Sub New()

  End Sub

  Public Property Set FileName As String
    p_FileName = FileName
    p_Extension = StrRightBack(FileName,".")
  End Property

  Public Property Get FileName As String
    FileName = p_FileName	
  End Property

  Public Function Extension() As String
    Extension = p_Extension	
  End Function

  Public Property Set FilePath As String
    p_FilePath = FilePath	
    If Right(p_FilePath,1)<>"\" Then
      p_FilePath = p_FilePath & "\"
    End If
  End Property

  Public Property Get FilePath As String
    FilePath = p_FilePath	
  End Property

  Public Property Set FullPathName As String
    Me.FilePath = StrLeftBack(FullPathName,"\")
    Me.FileName = StrRightBack(FullPathName,"\")
  End Property

  Public Property Get FullPathName As String
    FullPathName = p_FilePath & p_FileName	
  End Property

  Public Sub MakeDir(Byval strWhere As String)     
    ' *** This code by Andre Guirard @ IBM
    ' *** http://planetlotus.org/profiles/andre-guirard_22584
    ' *** Using an iterative method instead of recursive due to stack issues (see link above)
    On Error 76 Goto parentDoesNotExist 
    Dim stack$ 
    Const NL = { 
} 
    Do 
      Mkdir strWhere 
      On Error Goto 0 ' first success, stop trapping errors; avoid infinite loop. 
      strWhere = Strleft(stack, NL) ' "pop" a path for next iteration 
      stack = Mid$(stack, Len(strWhere)+2) 
failed: 
    Loop Until strWhere = "" 
    Exit Sub 
parentDoesNotExist: 
    ' This error code can indicate other problems, but assume missing parent. 
    ' If not, we get a different error (75) later when trying to create the parent. 
    Dim fpath$, fname$ 
    SplitFilepath strWhere, fpath, fname 
    If fpath = "" Then Error 76, "Invalid path: '" & strWhere & "'" 
    stack = strWhere & NL & stack ' "push" onto stack to retry later. 
    strWhere = fpath ' try a path one step shorter. 
    Resume failed 
  End Sub 

  ' ===== Private Supporting Functions =====

  Private Sub SplitFilePath(Byval fullpath$, dirpath$, filename$) 
    ' *** This subroutine by Andre Guirard @ IBM
    ' *** http://planetlotus.org/profiles/andre-guirard_22584
    ' *** Called from MakeDir()		
    Const DELIMS = {/\:} 
    While Instr(DELIMS, Right$(fullPath, 1)) ' discard final delimiter character... 
      fullpath = Left$(fullpath, Len(fullpath)-1) 
    Wend 
    Dim candidate$, i% 
    filename = Strtoken(fullpath, Left$(DELIMS, 1), -1) 
    For i = 2 To Len(DELIMS) 
      candidate = Strtoken(fullpath, Mid$(DELIMS, i, 1), -1) 
      If Len(candidate) < Len(filename) Then  				
        filename = candidate
      End If
    Next
    Dim fplen%
    fplen = Len(fullpath)-Len(filename)
    If fplen > 0 Then fplen = fplen - 1 
    dirpath = Left$(fullpath, fplen) 
  End Sub
End Class