Please, it is not the right forum ... ----- Original Message ----- From: "Mike Abney" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, July 17, 2001 5:46 PM Subject: Re: Object Oriented ?? > Santosh, > > This is not a simple question, but here's a simple answer: > > Objects are data and the operations on that data combined > into one package. > > But, as I said, it's not a simple question. So here's a longer answer. > > Paraphrasing the term's inventor, Alan Kay. (Note: It is somewhat debatable > whether he coined the term "object" for this, but he was AFAIK the first to > say "object-oriented".) > > Objects are self-contained units of information that allow you to send > messages to them that can: > - cause a change in the object's data (state) > - cause it to give you a response. > > Those two options are not mutually exclusive. As Kay says, "The big idea is > 'messaging'," but OO also requires minimally (this is also up for argument > in some camps) the following: > > - inheritance: the ability to define an object that builds upon the > definition of another object. (Ex. I create a Toy object and then > build a Ball object using much of the definition of Toy.) > > - polymorphism: the ability for many objects to understand the same > messages, but react/respond react/respond to them in different > ways. (Ex. A Ball responds differently to the message "freefall" than > a HeliumBalloon does. Hint: They go in different directions. ;-) ) > > - encapsulation: an object's implementation of a particular message > is not known nor needed by any objects that send that message. > (Ex. When I send the "freefall" message to Ball, I don't know whether > it's using a Newtonian algorithm contained within the Ball object or > it's actually delegating to a series of other physics-knowledgeable > objects. I just expect the Ball to drop and probably bounce in a way > that follows Newtonian physics.) > > There are other features that are commonly found in OO languages. Classes > are the big one. A class is an object definition that can be used to create > multiple objects that have the same structure and that respond to the same > messages. For more info, see > http://c2.com/cgi/wiki?ObjectOrientedProgramming. > > Also, there are several books available that cover OOP pretty well. One of > the first (and best, although I admit that I know one of the authors) is > Object-Oriented Programming by Peter Coad, Jill Nicola (ISBN# 013032616X). > The only problem you may have is that its examples are written in Smalltalk. > If you want to tackle it and do the examples yourself, I suggest going to > www.squeak.org for a Smalltalk environment. > > > ~Mike > > ----- Original Message ----- > From: "Santosh Varma" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Sent: Tuesday, July 17, 2001 3:48 AM > Subject: Object Oriented ?? > > > > can any one tell me what is meant by object oriented programming by a > simple > > and plain example ?? > > > > regards, > > > > Santosh Varma > > ___________________________________________________________________________ > To unsubscribe, send email to [EMAIL PROTECTED] and include in the body > of the message "signoff SERVLET-INTEREST". > > Archives: http://archives.java.sun.com/archives/servlet-interest.html > Resources: http://java.sun.com/products/servlet/external-resources.html > LISTSERV Help: http://www.lsoft.com/manuals/user/user.html ___________________________________________________________________________ To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff SERVLET-INTEREST". Archives: http://archives.java.sun.com/archives/servlet-interest.html Resources: http://java.sun.com/products/servlet/external-resources.html LISTSERV Help: http://www.lsoft.com/manuals/user/user.html
