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If both the object and the class contain attributes with the same name, the attribute in the object will shadow or hide the attribute in the class. I willdemonstrate the impact of this later.

If the search pattern described above is correct, we would expect the code in Listing 5 to display the values contained in each of the two new class variables belonging to the class named TestClass . Figure 2 shows the output produced by the code in Listing 5 and verifies that the search pattern described above is probably correct. The values stored in the new class variables are displayedin Figure 2 by the code in Listing 5 .

Figure 2 . Output of the code in Listing 5.
Display both class variables via one object ref01: ABCDref01: 1234

Display both class variables via the other object

The code in Listing 6 along with the output shown in Figure 10 shows unsurprisingly that the other object that was instantiated from TestClass can be used to access and display the same contents of the same two class variables.

Listing 6 . Display both class variables via the other object.
print("Display both class variables via the other object") print("ref02: " + ref02.classVar01)print("ref02: " + ref02.classVar02)

This is because class variables belonging to a class are shared among all objects instantiated from that class unless shadowed by an instance variablehaving the same name in an object of the class. This will be demonstrated in the programs that follow.

Typical class variable usage

Listing 16 shows a program that probably comes closer to the intended use of class variables than the code in the earlier program shown in Listing 15 . The output from the code shown in Listing 16 is shown in Figure 11 .

This program demonstrates that class variables are shared among the objects instantiated from a class. It also demonstrates that changes to class variablesin that class impact all of the objects instantiated from the class.

The class definition

Listing 7 shows the definition of the class for this program including the creation andinitialization a class variable named classVar . The class definition also includes a couple of methods that I will discuss later.

Listing 7 . The class definition.
class TestClass(object): classVar = [1,2,3,4]def modifyClassVar01(self): self.classVar.append("a")def printClassVar01(self): print(str(self)[10:40]+ ": " + str(self.classVar)) print("1 Display class var using class: " + str(TestClass.classVar))

Listing 7 also contains a print statement that prints the value of the variable named classVar by using the name of the class, TestClass , to access the variable. The output is shown in Figure 3 .

The output shown in Figure 3 faithfully reproduces the initial value of the class variable shown in the second line of text in Listing 7 .

Figure 3 . Output from the code in Listing 7.
1 Display class var using class: [1, 2, 3, 4]

Instantiate two objects from the class

Listing 8 instantiates two separate and distinct objects from the class named TestClass . Those objects' references are stored in the variables named ref01 and ref02 .

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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
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.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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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