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Three important OOP concepts

OOP is an abbreviation for Object-Oriented Programming. Most books on OOP will tell you that in order to understand OOP, you need to understand the following three concepts :

  • Encapsulation
  • Inheritance
  • Polymorphism

I will discuss the first two concepts in more detail in this and future modules. As near as I can tell, unlike C++ and Java, Python does not support polymorphism, atleast not in any significant way.

C++ and Java support two forms of polymorphism:

  • Compile-time polymorphism
  • Runtime polymorphism

Both of these depend on the "strongly-typed" nature of C++ and Java. Because Python is a "weakly-typed" (if typed at all) programming language, I don't know how to implement either form of polymorphism using Python. (However, if I am wrong on this, please let me know and I will be happy to learn how to implement polymorphism in Python.)

Generally, speaking, the concepts in the above list increase in difficulty going down the list from top to bottom. Therefore, I will begin with encapsulation and work my way down the list in successive modules.

What is an Object-Oriented Program ?

Many authors would answer this question something like the following:

An Object-Oriented Program consists of a group of cooperating objects, exchanging messages, for the purpose of achieving a common objective.

What is an object ?

An object is a software construct that encapsulates data, along with the ability to use or modify that data.

What is encapsulation ?

An interesting description of encapsulation was provided in an article by Rocky Lhotka regarding VB.NET. That description reads as follows:

"Encapsulation is the concept that an object should totally separate its interface from its implementation. All the data and implementation code for an object should be entirely hidden behind its interface. The idea is that we can create an interface (Public methods in a class) and, as long as that interface remains consistent, the application can interact with our objects. This remains true even if we entirely rewrite the code within a given method thus the interface is independent of the implementation."

I like this description, so I won't try to improve on it. I do need to point out that according to The Python Tutorial ,

"In fact, nothing in Python makes it possible to enforce data hiding -- it is all based upon convention."

Within that restriction, it is still possible to approximate encapsulation as described by Lhotka using Pythonprovided that appropriate conventions are adhered to.

Discussion and sample code

A real-world analogy -- a car radio

Abstract concepts, such as the concept of an object or encapsulation, can often be best understood by comparing them to real-world analogies. One imperfect, but fairly good analogy to a software object is the radio in your car.

The ability to store data

Your car radio probably has the ability to store data, and to allow you to use and modify that data at will. (However, you can only use and modify that data through use of the human interface that is provided by the manufacturer of the radio.) The data that can be stored in your car radio probably includes a list of five or more frequencies that correspond to your favorite radio stations.

Questions & Answers

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 to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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