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Define the subclass

The class named Subclass , which extends Superclass , is defined in Listing 2 . This class alsodefines a constructor method named __init__ , which in turn calls the __init__ method of Superclass , passing its own incoming parameters to the superclass constructor method.

Listing 2 . Define a subclass that extends or inherits from Superclass.
#Define a subclass that extends or inherits from Superclass class Subclass(Superclass):def __init__(self,name): Superclass.__init__(self,name)print(self.friend)

The method named __init__ in Subclass also prints the value of the variable named friend when it is executed.

When you instantiate a new object of a class that contains a method named __init__, that method is automatically called and a reference to theobject is automatically passed as the first parameter to the method. However, if you write code that explicitly calls __init__, you must explicitly pass thatparameter along with any other required parameters as shown in Listing 2.

Exercise the classes

The remaining program code is designed to exercise the classes and to illustrate the behavior of inheritance in Python. The code that exercises the classes begins in Listing 3 .

Display the value of the class variable

The code in Listing 3 gets and prints the initial value stored in the class variable named superclassVar , producing the output shown in Figure 1 .

Listing 3 . Display the value of the class variable.
#Code that exercises the classes print(Superclass.superclassVar)

As you can see, at this point in the program, the class variable contains the value True that was placed there when the class variable was created by the code in Listing 1 .

Figure 1 . Output from the code in Listing 3.

Instantiate a Subclass object

The code in Listing 4 instantiates an object of the class named Subclass passing "Joe" as a parameter to the __init__ method belonging to that class. (As you will recall, that __init__ method is automatically called when the object is instantiated.)

Figure 2 shows the output produced by executing the code in Listing 4 .

Listing 4 . Instantiate a Subclass object.
ref = Subclass("Joe") print(ref.superclassVar)

As you saw in Listing 2 , the __init__ method in the class named Subclass calls the method named __init__ in the class named Superclass passing both of its incoming parameters as parameters to the __init__ method in the class named Superclass . As you saw in Listing 1 , that method replaces the value True in superclassVar with one of its incoming parameters,which in this case is "Joe" .

The code in the method named __init__ in the class named Subclass in Listing 2 also prints the value of the variable named friend (which is created and initialized by the __init__ method in the class named Superclass in Listing 1 ) . This produces the first line of output text (Tom) shown in Figure 2 .

The code in Listing 4 also uses the reference to the Subclass object to get and print the value of the class variable named superclassVar from the class named Superclass , producing the second line of output text in Figure 2 (Joe) .

Questions & Answers

what is the stm
Brian Reply
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 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 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
How can I make nanorobot?
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
how can I make nanorobot?
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.
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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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