[go: up one dir, main page]

Open In App

Python OOPs Concepts

Last Updated : 05 Sep, 2024
Summarize
Comments
Improve
Suggest changes
Like Article
Like
Save
Share
Report
News Follow

Object Oriented Programming is a fundamental concept in Python, empowering developers to build modular, maintainable, and scalable applications. By understanding the core OOP principles—classes, objects, inheritance, encapsulation, polymorphism, and abstraction—programmers can leverage the full potential of Python’s OOP capabilities to design elegant and efficient solutions to complex problems.

What is Object-Oriented Programming in Python?

In Python object-oriented Programming (OOPs) is a programming paradigm that uses objects and classes in programming. It aims to implement real-world entities like inheritance, polymorphisms, encapsulation, etc. in the programming. The main concept of object-oriented Programming (OOPs) or oops concepts in Python is to bind the data and the functions that work together as a single unit so that no other part of the code can access this data. For more in-depth knowledge in Python OOPs concepts, try GeeksforGeeks Python course, it will gives you insights of Python programming

OOPs Concepts in Python

  • Class in Python
  • Objects in Python
  • Polymorphism in Python
  • Encapsulation in Python
  • Inheritance in Python
  • Data Abstraction in Python
Python OOPs

Python OOPs Concepts

Python Class 

A class is a collection of objects. A class contains the blueprints or the prototype from which the objects are being created. It is a logical entity that contains some attributes and methods. 

To understand the need for creating a class let’s consider an example, let’s say you wanted to track the number of dogs that may have different attributes like breed, and age. If a list is used, the first element could be the dog’s breed while the second element could represent its age. Let’s suppose there are 100 different dogs, then how would you know which element is supposed to be which? What if you wanted to add other properties to these dogs? This lacks organization and it’s the exact need for classes. 

Some points on Python class:  

  • Classes are created by keyword class.
  • Attributes are the variables that belong to a class.
  • Attributes are always public and can be accessed using the dot (.) operator. Eg.: Myclass.Myattribute

Class Definition Syntax:

class ClassName:
# Statement-1
.
.
.
# Statement-N

Creating an Empty Class in Python

In the above example, we have created a class named Dog using the class keyword.

Python
# Python3 program to
# demonstrate defining
# a class

class Dog:
    pass

Output

Python Objects

In object oriented programming Python, The object is an entity that has a state and behavior associated with it. It may be any real-world object like a mouse, keyboard, chair, table, pen, etc. Integers, strings, floating-point numbers, even arrays, and dictionaries, are all objects. More specifically, any single integer or any single string is an object. The number 12 is an object, the string “Hello, world” is an object, a list is an object that can hold other objects, and so on. You’ve been using objects all along and may not even realize it.

An object consists of:

  • State: It is represented by the attributes of an object. It also reflects the properties of an object.
  • Behavior: It is represented by the methods of an object. It also reflects the response of an object to other objects.
  • Identity: It gives a unique name to an object and enables one object to interact with other objects.

To understand the state, behavior, and identity let us take the example of the class dog (explained above). 

  • The identity can be considered as the name of the dog.
  • State or Attributes can be considered as the breed, age, or color of the dog.
  • The behavior can be considered as to whether the dog is eating or sleeping.

Creating an Object

This will create an object named obj of the class Dog defined above. Before diving deep into objects and classes let us understand some basic keywords that will be used while working with objects and classes.

Python
obj = Dog()

The Python self  

  1. Class methods must have an extra first parameter in the method definition. We do not give a value for this parameter when we call the method, Python provides it
  2. If we have a method that takes no arguments, then we still have to have one argument.
  3. This is similar to this pointer in C++ and this reference in Java.

When we call a method of this object as myobject.method(arg1, arg2), this is automatically converted by Python into MyClass.method(myobject, arg1, arg2) – this is all the special self is about.

Note: For more information, refer to self in the Python class

The Python __init__ Method 

The __init__ method is similar to constructors in C++ and Java. It is run as soon as an object of a class is instantiated. The method is useful to do any initialization you want to do with your object. Now let us define a class and create some objects using the self and __init__ method.

Creating a class and object with class and instance attributes

Python
class Dog:

    # class attribute
    attr1 = "mammal"

    # Instance attribute
    def __init__(self, name):
        self.name = name

# Driver code
# Object instantiation
Rodger = Dog("Rodger")
Tommy = Dog("Tommy")

# Accessing class attributes
print("Rodger is a {}".format(Rodger.__class__.attr1))
print("Tommy is also a {}".format(Tommy.__class__.attr1))

# Accessing instance attributes
print("My name is {}".format(Rodger.name))
print("My name is {}".format(Tommy.name))

Output
Rodger is a mammal
Tommy is also a mammal
My name is Rodger
My name is Tommy

Creating Classes and objects with methods

Here, The Dog class is defined with two attributes:

  • attr1 is a class attribute set to the value “mammal“. Class attributes are shared by all instances of the class.
  • __init__ is a special method (constructor) that initializes an instance of the Dog class. It takes two parameters: self (referring to the instance being created) and name (representing the name of the dog). The name parameter is used to assign a name attribute to each instance of Dog.
    The speak method is defined within the Dog class. This method prints a string that includes the name of the dog instance.

The driver code starts by creating two instances of the Dog class: Rodger and Tommy. The __init__ method is called for each instance to initialize their name attributes with the provided names. The speak method is called in both instances (Rodger.speak() and Tommy.speak()), causing each dog to print a statement with its name.

Python
class Dog:

    # class attribute
    attr1 = "mammal"

    # Instance attribute
    def __init__(self, name):
        self.name = name
        
    def speak(self):
        print("My name is {}".format(self.name))

# Driver code
# Object instantiation
Rodger = Dog("Rodger")
Tommy = Dog("Tommy")

# Accessing class methods
Rodger.speak()
Tommy.speak()

Output
My name is Rodger
My name is Tommy

Note: For more information, refer to Python Classes and Objects

Python Inheritance

In Python object oriented Programming, Inheritance is the capability of one class to derive or inherit the properties from another class. The class that derives properties is called the derived class or child class and the class from which the properties are being derived is called the base class or parent class. The benefits of inheritance are:

  • It represents real-world relationships well.
  • It provides the reusability of a code. We don’t have to write the same code again and again. Also, it allows us to add more features to a class without modifying it.
  • It is transitive in nature, which means that if class B inherits from another class A, then all the subclasses of B would automatically inherit from class A.

Types of Inheritance

  • Single Inheritance: Single-level inheritance enables a derived class to inherit characteristics from a single-parent class.
  • Multilevel Inheritance: Multi-level inheritance enables a derived class to inherit properties from an immediate parent class which in turn inherits properties from his parent class. 
  • Hierarchical Inheritance: Hierarchical-level inheritance enables more than one derived class to inherit properties from a parent class.
  • Multiple Inheritance: Multiple-level inheritance enables one derived class to inherit properties from more than one base class.

Inheritance in Python

In the above article, we have created two classes i.e. Person (parent class) and Employee (Child Class). The Employee class inherits from the Person class. We can use the methods of the person class through the employee class as seen in the display function in the above code. A child class can also modify the behavior of the parent class as seen through the details() method.

Python
# Python code to demonstrate how parent constructors
# are called.

# parent class
class Person(object):

    # __init__ is known as the constructor
    def __init__(self, name, idnumber):
        self.name = name
        self.idnumber = idnumber

    def display(self):
        print(self.name)
        print(self.idnumber)
        
    def details(self):
        print("My name is {}".format(self.name))
        print("IdNumber: {}".format(self.idnumber))
    
# child class
class Employee(Person):
    def __init__(self, name, idnumber, salary, post):
        self.salary = salary
        self.post = post

        # invoking the __init__ of the parent class
        Person.__init__(self, name, idnumber)
        
    def details(self):
        print("My name is {}".format(self.name))
        print("IdNumber: {}".format(self.idnumber))
        print("Post: {}".format(self.post))


# creation of an object variable or an instance
a = Employee('Rahul', 886012, 200000, "Intern")

# calling a function of the class Person using
# its instance
a.display()
a.details()

Output
Rahul
886012
My name is Rahul
IdNumber: 886012
Post: Intern

Note: For more information, refer to our Inheritance in Python tutorial.

Python Polymorphism

In object oriented Programming Python, Polymorphism simply means having many forms. For example, we need to determine if the given species of birds fly or not, using polymorphism we can do this using a single function.

Polymorphism in Python

This code demonstrates the concept of Python oops inheritance and method overriding in Python classes. It shows how subclasses can override methods defined in their parent class to provide specific behavior while still inheriting other methods from the parent class.

Python
class Bird:
  
    def intro(self):
        print("There are many types of birds.")

    def flight(self):
        print("Most of the birds can fly but some cannot.")

class sparrow(Bird):
  
    def flight(self):
        print("Sparrows can fly.")

class ostrich(Bird):

    def flight(self):
        print("Ostriches cannot fly.")

obj_bird = Bird()
obj_spr = sparrow()
obj_ost = ostrich()

obj_bird.intro()
obj_bird.flight()

obj_spr.intro()
obj_spr.flight()

obj_ost.intro()
obj_ost.flight()

Output
There are many types of birds.
Most of the birds can fly but some cannot.
There are many types of birds.
Sparrows can fly.
There are many types of birds.
Ostriches cannot fly.

Note: For more information, refer to our Polymorphism in Python Tutorial.

Python Encapsulation

In Python object oriented programming, Encapsulation is one of the fundamental concepts in object-oriented programming (OOP). It describes the idea of wrapping data and the methods that work on data within one unit. This puts restrictions on accessing variables and methods directly and can prevent the accidental modification of data. To prevent accidental change, an object’s variable can only be changed by an object’s method. Those types of variables are known as private variables.

A class is an example of encapsulation as it encapsulates all the data that is member functions, variables, etc.

Encapsulation in Python

In the above example, we have created the c variable as the private attribute. We cannot even access this attribute directly and can’t even change its value.

Python
# Python program to
# demonstrate private members
# "__" double underscore represents private attribute. 
# Private attributes start with "__".

# Creating a Base class
class Base:
    def __init__(self):
        self.a = "GeeksforGeeks"
        self.__c = "GeeksforGeeks" 

# Creating a derived class
class Derived(Base):
    def __init__(self):

        # Calling constructor of
        # Base class
        Base.__init__(self)
        print("Calling private member of base class: ")
        print(self.__c)


# Driver code
obj1 = Base()
print(obj1.a)

# Uncommenting print(obj1.c) will
# raise an AttributeError

# Uncommenting obj2 = Derived() will
# also raise an AtrributeError as
# private member of base class
# is called inside derived class

Output
GeeksforGeeks

Note: for more information, refer to our Encapsulation in Python Tutorial.

Data Abstraction 

It hides unnecessary code details from the user. Also,  when we do not want to give out sensitive parts of our code implementation and this is where data abstraction came.

Data Abstraction in Python can be achieved by creating abstract classes.

Python
class Rectangle:
    def __init__(self, length, width):
        self.__length = length  # Private attribute
        self.__width = width    # Private attribute

    def area(self):
        return self.__length * self.__width

    def perimeter(self):
        return 2 * (self.__length + self.__width)


rect = Rectangle(5, 3)
print(f"Area: {rect.area()}")          # Output: Area: 15
print(f"Perimeter: {rect.perimeter()}")  # Output: Perimeter: 16

# print(rect.__length)  # This will raise an AttributeError as length and width are private attributes

Output
Area: 15
Perimeter: 16


Object Oriented Programming in Python | Set 2 (Data Hiding and Object Printing)

Python OOPs – FAQs

What are the 4 pillars of OOP Python?

The 4 pillars of object-oriented programming (OOP) in Python (and generally in programming) are:

  • Encapsulation: Bundling data (attributes) and methods (functions) that operate on the data into a single unit (class).
  • Abstraction: Hiding complex implementation details and providing a simplified interface.
  • Inheritance: Allowing a class to inherit attributes and methods from another class, promoting code reuse.
  • Polymorphism: Using a single interface to represent different data types or objects.

Is OOP used in Python?

Yes, Python fully supports object-oriented programming (OOP) concepts. Classes, objects, inheritance, encapsulation, and polymorphism are fundamental features of Python.

Is Python 100% object-oriented?

Python is a multi-paradigm programming language, meaning it supports multiple programming paradigms including procedural, functional, and object-oriented programming. While Python is predominantly object-oriented, it also allows for procedural and functional programming styles.

What is __init__ in Python?

__init__ is a special method (constructor) in Python classes. It’s automatically called when a new instance (object) of the class is created. Its primary purpose is to initialize the object’s attributes or perform any setup required for the object.

class MyClass:
def __init__(self, arg1, arg2):
self.arg1 = arg1
self.arg2 = arg2

What is super() in Python?

super() is used to call methods of a superclass (parent class) from a subclass (child class). It returns a proxy object that delegates method calls to the superclass. This is useful for accessing inherited methods that have been overridden in a subclass.

class ChildClass(ParentClass):
def __init__(self, arg1, arg2):
super().__init__(arg1) # Calls the __init__() method of the ParentClass
self.arg2 = arg2

Why is self used in Python?

'self' is a convention in Python used to refer to the instance of a class (object) itself. It’s the first parameter of instance methods and refers to the object calling the method. It allows methods to access and manipulate attributes (variables) that belong to the instance.

class MyClass:
def __init__(self, name):
self.name = name

def greet(self):
return f"Hello, {self.name}!"

obj = MyClass("Alice")
print(obj.greet()) # Output: Hello, Alice!


Similar Reads

Shuffle a deck of card with OOPS in Python
The objective is to distribute a deck of cards among two players. The code for the Shuffle Deck of Cards in Python can be used to shuffle the cards. The shuffle method, which is a built-in feature of the random library, is used to mix and randomize the order of the data before printing it. Prerequisites: Python Classes and Objects Steps to Shuffle
3 min read
Python OOPS - Aggregation and Composition
In this article, we will compare and highlight the features of aggregation and Composition in Python OOPS. Concept of Inheritance Inheritance is a mechanism that allows us to take all of the properties of another class and apply them to our own. The parent class is the one from which the attributes and functions are derived (also called as Base Cla
5 min read
30 OOPs Interview Questions and Answers (2024) Updated
Object-oriented programming, or OOPs, is a programming paradigm that implements the concept of objects in the program. It aims to provide an easier solution to real-world problems by implementing real-world entities such as inheritance, abstraction, polymorphism, etc. in programming. OOPs concept is widely used in many popular languages like Java,
15+ min read
Top 10 Advance Python Concepts That You Must Know
Python is a high-level, object-oriented programming language that has recently been picked up by a lot of students as well as professionals due to its versatility, dynamic nature, robustness, and also because it is easy to learn. Not only this, it is now the second most loved and preferred language after JavaScript and can be used in almost all tec
6 min read
Important differences between Python 2.x and Python 3.x with examples
In this article, we will see some important differences between Python 2.x and Python 3.x with the help of some examples. Differences between Python 2.x and Python 3.x Here, we will see the differences in the following libraries and modules: Division operatorprint functionUnicodexrangeError Handling_future_ modulePython Division operatorIf we are p
5 min read
Reading Python File-Like Objects from C | Python
Writing C extension code that consumes data from any Python file-like object (e.g., normal files, StringIO objects, etc.). read() method has to be repeatedly invoke to consume data on a file-like object and take steps to properly decode the resulting data. Given below is a C extension function that merely consumes all of the data on a file-like obj
3 min read
Python | Add Logging to a Python Script
In this article, we will learn how to have scripts and simple programs to write diagnostic information to log files. Code #1 : Using the logging module to add logging to a simple program import logging def main(): # Configure the logging system logging.basicConfig(filename ='app.log', level = logging.ERROR) # Variables (to make the calls that follo
2 min read
Python | Add Logging to Python Libraries
In this article, we will learn how to add a logging capability to a library, but don’t want it to interfere with programs that don’t use logging. For libraries that want to perform logging, create a dedicated logger object, and initially configure it as shown in the code below - Code #1 : C/C++ Code # abc.py import logging log = logging.getLogger(_
2 min read
Python | Index of Non-Zero elements in Python list
Sometimes, while working with python list, we can have a problem in which we need to find positions of all the integers other than 0. This can have application in day-day programming or competitive programming. Let's discuss a shorthand by which we can perform this particular task. Method : Using enumerate() + list comprehension This method can be
6 min read
MySQL-Connector-Python module in Python
MySQL is a Relational Database Management System (RDBMS) whereas the structured Query Language (SQL) is the language used for handling the RDBMS using commands i.e Creating, Inserting, Updating and Deleting the data from the databases. SQL commands are case insensitive i.e CREATE and create signify the same command. In this article, we will be disc
2 min read
Python - Read blob object in python using wand library
BLOB stands for Binary Large OBject. A blob is a data type that can store binary data. This is different than most other data types used in databases, such as integers, floating point numbers, characters, and strings, which store letters and numbers. BLOB is a large complex collection of binary data which is stored in Database. Basically BLOB is us
2 min read
twitter-text-python (ttp) module - Python
twitter-text-python is a Tweet parser and formatter for Python. Amongst many things, the tasks that can be performed by this module are : reply : The username of the handle to which the tweet is being replied to. users : All the usernames mentioned in the tweet. tags : All the hashtags mentioned in the tweet. urls : All the URLs mentioned in the tw
3 min read
Reusable piece of python functionality for wrapping arbitrary blocks of code : Python Context Managers
Context Managers are the tools for wrapping around arbitrary (free-form) blocks of code. One of the primary reasons to use a context manager is resource cleanliness. Context Manager ensures that the process performs steadily upon entering and on exit, it releases the resource. Even when the wrapped code raises an exception, the context manager guar
7 min read
Creating and updating PowerPoint Presentations in Python using python - pptx
python-pptx is library used to create/edit a PowerPoint (.pptx) files. This won't work on MS office 2003 and previous versions. We can add shapes, paragraphs, texts and slides and much more thing using this library. Installation: Open the command prompt on your system and write given below command: pip install python-pptx Let's see some of its usag
4 min read
Python Debugger – Python pdb
Debugging in Python is facilitated by pdb module (python debugger) which comes built-in to the Python standard library. It is actually defined as the class Pdb which internally makes use of bdb(basic debugger functions) and cmd (support for line-oriented command interpreters) modules. The major advantage of pdb is it runs purely in the command line
5 min read
Filter Python list by Predicate in Python
In this article, we will discuss how to filter a python list by using predicate. Filter function is used to filter the elements in the given list of elements with the help of a predicate. A predicate is a function that always returns True or False by performing some condition operations in a filter method Syntax: filter(predicate, list) where, list
2 min read
Python: Iterating With Python Lambda
In Python, the lambda function is an anonymous function. This one expression is evaluated and returned. Thus, We can use lambda functions as a function object. In this article, we will learn how to iterate with lambda in python. Syntax: lambda variable : expression Where, variable is used in the expressionexpression can be an mathematical expressio
2 min read
Python Value Error :Math Domain Error in Python
Errors are the problems in a program due to which the program will stop the execution. One of the errors is 'ValueError: math domain error' in Python. In this article, you will learn why this error occurs and how to fix it with examples. What is 'ValueError: math domain error' in Python?In mathematics, we have certain operations that we consider un
4 min read
Creating Your Own Python IDE in Python
In this article, we are able to embark on an adventure to create your personal Python Integrated Development Environment (IDE) the usage of Python itself, with the assistance of the PyQt library. What is Python IDE?Python IDEs provide a characteristic-rich environment for coding, debugging, and going for walks in Python packages. While there are ma
3 min read
GeeksforGeeks Python Foundation Course - Learn Python in Hindi!
Python - it is not just an ordinary programming language but the doorway or basic prerequisite for getting into numerous tech domains including web development, machine learning, data science, and several others. Though there's no doubt that the alternatives of Python in each of these respective areas are available - but the dominance and popularit
5 min read
Python math.sqrt() function | Find Square Root in Python
sqrt() function returns square root of any number. It is an inbuilt function in Python programming language. In this article, we will learn more about the Python Program to Find the Square Root. sqrt() Function We can calculate square root in Python using the sqrt() function from the math module. In this example, we are calculating the square root
3 min read
Python Image Editor Using Python
You can create a simple image editor using Python by using libraries like Pillow(PIL) which will provide a wide range of image-processing capabilities. In this article, we will learn How to create a simple image editor that can perform various operations like opening an image, resizing it, blurring the image, flipping and rotating the image, and so
13 min read
Python | Set 4 (Dictionary, Keywords in Python)
In the previous two articles (Set 2 and Set 3), we discussed the basics of python. In this article, we will learn more about python and feel the power of python. Dictionary in Python In python, the dictionary is similar to hash or maps in other languages. It consists of key-value pairs. The value can be accessed by a unique key in the dictionary. (
5 min read
Learn DSA with Python | Python Data Structures and Algorithms
This tutorial is a beginner-friendly guide for learning data structures and algorithms using Python. In this article, we will discuss the in-built data structures such as lists, tuples, dictionaries, etc, and some user-defined data structures such as linked lists, trees, graphs, etc, and traversal as well as searching and sorting algorithms with th
15+ min read
Why we write #!/usr/bin/env python on the first line of a Python script?
The shebang line or hashbang line is recognized as the line #!/usr/bin/env python. This helps to point out the location of the interpreter intended for executing a script, especially in Unix-like operating systems. For example, Linux and macOS are Unix-like operating systems whose executable files normally start with a shebang followed by a path to
2 min read
Setting up ROS with Python 3 and Python OpenCV
Setting up a Robot Operating System (ROS) with Python 3 and OpenCV can be a powerful combination for robotics development, enabling you to leverage ROS's robotics middleware with the flexibility and ease of Python programming language along with the computer vision capabilities provided by OpenCV. Here's a step-by-step guide to help you set up ROS
3 min read
What is Python Used For? | 7 Practical Python Applications
Python is an interpreted and object-oriented programming language commonly used for web development, data analysis, artificial intelligence, and more. It features a clean, beginner-friendly, and readable syntax. Due to its ecosystem of libraries, frameworks, and large community support, it has become a top preferred choice for developers in the ind
9 min read
How to Install python-dotenv in Python
Python-dotenv is a Python package that is used to manage & store environment variables. It reads key-value pairs from the “.env” file. How to install python-dotenv?To install python-dotenv using PIP, open your command prompt or terminal and type in this command. pip install python-dotenvVerifying the installationTo verify if you have successful
3 min read
Future of Python : Exploring Python 4.0
The future of Python 4.0 is a topic of great anticipation and speculation within the tech community. Guido van Rossum, the creator of Python, offers exclusive insights into what might lie ahead for this popular programming language. With Python 3.9 approaching its release, many are curious about t the potential for Python 4.0. This article explores
8 min read
Top 10 Python Built-In Decorators That Optimize Python Code Significantly
Python is a widely used high-level, general-purpose programming language. The language offers many benefits to developers, making it a popular choice for a wide range of applications including web development, backend development, machine learning applications, and all cutting-edge software technology, and is preferred for both beginners as well as
12 min read
Article Tags :
Practice Tags :
three90RightbarBannerImg