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A python class definition is a set of plans

The same is true for software objects. In order to create a software object in Python, it is necessary for someone to first create a plan.In Python, we refer to that plan as a class . The class is defined by a Python programmer. Once the class definition is available, that programmer (or other programmers) , can use it to produce large numbers of nearly identical objects.

An instance of a class

If we were standing at the output end of the factory that produces car radios, we might pick up a new radio and say that it is an instance of the plans used to produce the radio. (Unless they were object-oriented programmers, the people around us might think we were a little odd when they hear us say that.) However, it is common jargon to refer to a software object as an instance of a class.

To instantiate an object

Furthermore, somewhere along the way, someone turned the word instance into a verb, and it is also common jargon to say that when creating a new object, we are instantiating an object.

Program code

As mentioned above, I will explain a program that uses the analogy of a car radio to illustrate several aspects of Python classes and objects.

I will explain this program in fragments. A complete listing of the program is provided in Listing 9 near the end of the module. The output from running the program is shown in Figure 6 . Because this is an overview module, this explanation will gloss over various details. I willrevisit and explain many of those details in future modules.

Manufacture a three-button radio

As you will see if you examine Listing 9 , this program defines a class named Radio . That class can be used to create objects that simulate car radios havingthree station-selector buttons and a scan button. I will explain that class later. First I will explain how to use the class.

Listing 1 shows the code necessary to create (instantiate) a single instance of the Radio class and to store that object's reference in a variable named radio01 . (In OOP jargon we say that an object is an instance of a class.) This simulates the manufacturing of the radio and the installation of the radio in a car.

Listing 1 . Manufacture a three-button radio.
#Manufacture a 3-button radio radio01 = Radio()

As a practical matter, the code required to instantiate a Python object looks just like the code required to call a function having the same name asthe class from which the object is being instantiated. In my opinion, this causes Python to be a little less readable than Java, which uses a specialsyntax to create an object.

Scan for available stations

Next we want to program the station-selector buttons to cause our favorite radio stations to be played when we press a button. First, however, we willsimulate pressing the scan button on the radio to learn about the stations that are available in the area.

Listing 2 uses the reference variable named radio01 to call a method named scan belonging to the object referred to by radio01 . As you will see later when we examine the class definition, the scan method requires the name of the city as an incoming parameter and returns a reference to a dictionary that relatesfrequencies to radio station call signs in that city. The returned reference is stored in the variable named radio01Stations .

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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.
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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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