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Introduction to Class Programming

By Dante Salvador, published on 05 Sep 2003
Page 4 of 12
  1. Introduction
  2. What is a Class
  3. Why Use Class?
  4. Fundamental Concepts About Class
  5. Building Your First Class
  6. Properties Of a Class
  7. Property Get/Let
  8. Read-Only Property
  9. Write-only property
  10. Method of a Class
  11. Choosing Between Methods or Properties
  12. Summary

Fundamental Concepts About Class

Before diving into object-oriented programming let try to understand some concepts that will help you later in the articles.

Encapsulation

Encapsulation is the process of combining logically related procedure and data in one class/objects. This way, each object is insulated (separated, protected) from the rest of the program. Because the object is only using data contained within it or passed to it. And it executes only internal procedures. It does not contain any global or public variables, and does not require any external procedures to execute its members. The data and behaviors of an encapsulated object can only be accessed and manipulated through its properties and public methods. Thus encapsulation provides several advantages for you as a programmer.  You can protect data from corruption by other objects or parts of the program. You can hide low-level, complex implementation details from the rest of the program, which results in the ability to implement a simple public interface to a more complex set of private member. It is also easier to maintain legacy code or add new members to the object without affecting any procedures that currently call the object. You can to debug individual object and ensure that a bug in one object will not affect some other part of the system in an apparently unconnected way. And lastly, you can reuse the object or by other programmer, improving the productivity.

Polymorphism

Polymorphism is the ability of different classes to expose similar (or identical) interfaces to the outside. The most unmistakable kind of polymorphism in Visual Basic is forms and controls. For example, TextBox and PictureBox controls are completely different objects, but they have some properties and methods in common, such as Left property and Move method. As a programmer, you don't need to worry about how they implement its functionality, instead, all you have to do is to apply it to a supported object and pass a correct value as arguments.

Inheritance

Inheritance is the ability to derive a new class (the derived or inherited class) from another class (the base class). The derived class automatically inherits the properties and methods of the base class. For example, you could define a generic Person class with properties such as FirstName and Lastname and then use it as a base for more specific classes (for example, Student, Faculty, and so on) that inherit all those generic properties. You could then add specific members, such as BirthDate and StudentID for the Student class and FacultyID for the Faculty class. Thus it reduce the amount of code on your class itself, therefore simplifies the job of the class author. Unfortunately, Visual Basic doesn't support inheritance, at least not in its more mature form of implementation inheritance. 

Comments

  1. Vincent Bloemen
    26 Jun 2009 at 13:14

    Wouw, thanks for this great explanation on how to use and make classes. I always coded in VB with function in normal Modules, now i'm going one step further... Trying it out...

  2. jakaria pervez
    23 Jun 2009 at 10:37

    Great Tutorial !! Helped me a lot

  3. The Nguyen
    07 Mar 2009 at 10:54
    This is great tutorial! Thank you sooooo much.
  4. Edi Winarko
    07 Jun 2008 at 11:55

    [quote user="Developer Fusion Bot"]

    This thread is for discussions of Introduction to Class Programming.

    [/quote]

    This was the best explanation to "class", I have ever come across. Hats off to you.

  5. Bhavani Josyula
    12 Jul 2007 at 12:36

    Hello Sir,

    I have just seen u'r examples for class module.u'r explaination is simply superb!!!!

    now i clearly understood the class module concept in VB.

     

    Thanks

    Bhavani Josyula

  6. Craig Nelson
    15 May 2007 at 16:10
    This was a very good fundamental article on the use of classes in VB. looking forward to additional more advance content
  7. davulcu
    16 May 2006 at 11:35

    It s a great sample about the class programming. However, it s still uncertain for me where I can use this in real life.

    Can anyone give me an example ?

  8. kirov
    05 Oct 2005 at 19:12

    what kind of help you wants from me. i mean to clear out your visual basic basics by giving you some tutorials or anything else. bye

  9. wan_rids2020
    29 Sep 2005 at 12:25
    hello sir, can you teach me the visual basic programing and where to start because i don't have a basic in this software. before this, i was try to learn this programe from e_book but it's looking so hurt to learn without a teacher.
    I would appericiate if u can show me the way to learn this programe.
    TQ
  10. T. Lowell Dent
    16 Jul 2005 at 02:59
    Thanks, Dante Salvador, for your excellent and lucid tutorial on Class Programming.
    I have worn Google to a frazzle looking for help. most of which was comprised of a few samples.
    You have helped "elucidate" me with both the why and how-to and that is no small task.
    Thanks so much for your efforts and help.
  11. kirov
    09 Jun 2005 at 17:34

    What a tutorial !! man i like it. this tutorial shows me another side of visual basic wow!!

  12. satinder_jit
    23 Dec 2004 at 13:40

    This is really a good tutorial on Visual Basic. I was really coinfused between let, get properties. But this is the final place which solved ll my problems

  13. Sparvhok
    22 Oct 2003 at 11:52

    vbexplorer.com has also an excellent oop tutorial, if youre looking for some more,
    and I have found a german article at vbarchiv.de that seems very good (i can
    tell because I studied german when in grad. school, swe).


    Maybe I should try an translate it to english...

  14. Joe Campbell
    20 Sep 2003 at 06:32

  15. leisha
    10 Sep 2003 at 17:41
    At one time I studied programming in Pascal & Fortran --- have forgotten lots of basics....I have read thru many VB tutorials etc but never have I so clearly had the 'light bulb' go on.  Thank-you for a well organized presentation.  Look forward to your future articles.
  16. Developer Fusion Bot
    01 Jan 1999 at 00:00

    This thread is for discussions of Introduction to Class Programming.

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