<< Chapter < Page Chapter >> Page >
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

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
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.
Harper
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!





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
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Itse 1359 introduction to scripting languages: python' conversation and receive update notifications?

Ask