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Expose the interface and hide the implementation

As in the steering mechanism for a car, a common approach in OOP is to "hide the implementation" and to "expose the interface" through encapsulation.

Inheritance example

Another important aspect of OOP is inheritance. Let's form an analogy with the teenager who is building a hotrod. That teenager doesn't normally start witha large chunk of steel and carve an engine out of it. Rather, the teenager will usually start with an existing engine and make improvements to it.

OOP lingo

In OOP lingo, that teenager extends the existing engine, derives from the existing engine, inherits from the existing engine, or subclasses the existing engine (depending on which author is describing the process) .

Just like in "souping up" an engine for a hotrod, a very common practice in OOP is to create new improved classes and objects by extending existing classdefinitions.

Extending the Game class

When you use Visual C# to create a new XNA game project, the IDE creates skeleton code for a new class. As you will learn later in this course, it isthen up to you to put some meat on the skeleton and turn it into a game. The first executable statement in the skeleton code is shown in Listing 1 .

Listing 1 . Extending the Game class.

public class Game1 : Microsoft.Xna.Framework.Game

The code in Listing 1 is the first executable statement in the definition of a new class named Game1 (or whatever name you give the new project) . The definition of the new class extends an existing class named Game , which resides in the Microsoft.Xna.Framework namespace. The existing class named Game , is the main controller for your new game. I will have much more to say about the Game class in a future module.

Reuse, don't reinvent

One of the major arguments in favor of OOP is that it provides a formal mechanism that encourages the reuse of existing programming elements. One of themottos of OOP is "reuse, don't reinvent."

Polymorphism example

A third important aspect of OOP is polymorphism. This is a Greek word meaning something like one name, many forms . This is a little more difficult to explain in non-programming terminology. However, we will stretch our imaginationa little and say that polymorphism is somewhat akin to the automatic transmission in your car. In my Honda, for example, the automatic transmissionhas four different methods or functions known collectively as Drive (in addition to the functions of Reverse, Park, and Neutral) .

Select Drive to go forward

As an operator of the automobile, I simply select Drive (meaning go forward) . Depending on various conditions at runtime, the automatic transmission systemdecides which version of the Drive function to use in every specific situation. The specific version of the function that is used is based on the currentconditions (speed, incline, etc.) . This is somewhat analogous to what we will refer to in a subsequent tutorial module as runtime polymorphism.

Object-oriented programming vocabulary

OOP involves a whole new vocabulary (or jargon) which is different from or supplemental to the vocabulary of procedural programming.

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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