Object-Oriented Programming in Python

Honey Thakuria — Sat, 20 Jun 2020 06:23:07 +0000

There is always skepticism among the developers, whether Python is an object-oriented language or it's just a more of Procedural language.

This post will be an answer to such skepticism. Before getting a deep dive into it, let's focus on the fundamental features which Python offers.

Features of Python:

1.Simple : English like human readable code

2.Free & Open Source: FLOSS License.

3.Object Oriented: Organizing the program by combining data and functionality and wrapping inside object of type defined by Class.

4.High Level: We don't need to worry about memory management.

5.Interpreted: We just need to run the source code, it internally converts it into byte code and then translates it to the native language of the computer and then runs it.

6.Dynamic & Weak Typed : Compiled at run time & Variables can be implicitly coerced to unrelated types.

Why to take object-oriented approach?

When we have larger problems or when we want to focus on organizing, reusing, minimizing the code, it can be helpful.

Key terminologies used in object-oriented programming?

Classes: It creates a new type.
Object: These are instances of the class. They can store data in variables called fields and also can have functionalities belonging to the class called methods and can store them at the instance or class level.

A more deep dive into the terminologies will be covered in the next section where we will write some relevant code.

Problem Statement:

Keeping track of Students in a School with some common reusable properties like name, age, and some specific properties such as school population, student fees.
It should be designed in such a way that in the future if a new entity like a Teacher or office staff comes, it can reuse the code.

Base class: SchoolMember

class SchoolMember:
__populationSchool = 0

def __init__(self,name,age,type):
    self.name = name
    self.age = age
    self.type = type
    SchoolMember.__populationSchool +=1

def tell(self):
    print("My name is {0}, My age is {1} and I'm a {2}".format(self.name,self.age,self.type))

@classmethod
def get_schoolPop(cls):
    print(f"School Population is {cls.__populationSchool}")

Terminologies used:

Class :A new class can be created using Class statement and name of class. Eg: class SchoolMember:
Methods: Similar to ordinary functions defined using def with one addition first parameter, which refers to Object itself. self is just convention, can rename it too. Eg: def tell(self):
init : A method that is called as soon as the class object gets created.
Class Variable: Variables which can be used by all the instances of the class and share memory. Eg: __populationSchool
Object Variables: Owned by each individual object/instance of the class. Eg: name,age
Private Members: Members having double underscore prefixed to them. It can be used within the class only. Eg: __populationSchool
@classmethod: Decorator to define the class method which shares the memory across all the instance.

Child class inheriting Base class:

class Student(SchoolMember):
__studentPopulation = 0
def __init__(self,name,age,marks,fee):
    SchoolMember.__init__(self,name,age,"Student")
    self.__marks = 80
    self.fee = fee
    Student.__studentPopulation += 1


def studentInfo(self):
    print(f"Student name is {self.name} and his marks is {self.__marks}")

@classmethod
def get_studentPop(cls):
    print(f"Student Population is {cls.__studentPopulation}")

Added terminologies:

Inheritance: Reusing the code across classes by implementing relationships across classes. Eg:class Student(SchoolMember): As the name, age are reusable properties, they are inherited from School member and student-specific properties like fee, marks are added to Student class. Inherited properties can be used in new classes like Teacher, Office Admin, etc, too.

Creation of Object and usage.

if(__name__ == "__main__"):
   s1 = Student("Honey",27,80,90000)
   s2 = Student("Shubhi",27,80,920000) 
   s3 = Student("Stu3",27,80,90000)
   s3.get_studentPop() //#Student Population is 3
   s1.tell() //#My name is Honey, My age is 27 and I'm a Student
   s1.studentInfo() //#Student name is Honey and his marks is 80

Complete code can be found here: https://github.com/honey93/CodingProblems/blob/master/Python/oopSchool.py
Fork the code, try to put your imagination and come up with Teacher, Office admin, etc classes and master the skills.

I hope you liked and learned something out of it.

About me: https://honeythakuria.com

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