Introduction to Object Oriented Programming
Object Oriented Programming (OOP) is a programming paradigm where data and functions are combined into reusable components called objects. OOP allows complex programs to be modular and more manageable by encapsulating related functionality into a single component.
This approach to programming is based on four fundamental principles: Polymorphism, Encapsulation, Inheritance, and Data Abstraction.
Classes and Objects
In OOP, the building block of the program is a Class, which is a blueprint that defines the attributes and behavior of an object. An object, on the other hand, is an instance of a Class that has its own set of data members and member functions.
Classes and objects are the foundation of Object Oriented Programming.
Creating a Python Class
Python is an interpreted, high-level, general-purpose programming language that supports multiple programming paradigms, including object-oriented, functional, and procedural programming. In Python, a Class is defined using the class reserved keyword.
A typical class definition includes data members and member functions that define the properties and behavior of an object.
Definition of Python Class
A Python Class is a blueprint or template that defines the attributes and behaviors of an object. A Class encapsulates data and methods into a single unit, which can be used to create multiple objects with the same properties and behavior.
In Python, a Class consists of data members and member functions. Data Members: Data members are variables that hold data specific to a Class.
These variables are initialized with a value when the Class is instantiated, and they can be accessed using the dot notation. Member Functions: Member functions define the behavior of a Class.
They are used to perform operations on the data members of a Class. Member functions can be of two types: Instance methods and Static methods.
Creating a Class in Python
In Python, a Class is defined using the class reserved keyword, followed by the Class name and a colon. The Class definition contains the data members and member functions that define the properties and behavior of the Class.
class Class_Name:
data_member_1 = value_1
data_member_2 = value_2
def member_function_1(self, parameter_1):
# code block
return output
In the above example, we can see that a Class named Class_Name is defined. It contains two data members: data_member_1 and data_member_2.
It also contains a member function named member_function_1 that takes a parameter named parameter_1 and returns an output.
Instantiating a Class in Python
Once a Class is defined, we can create an object of the Class, which is an instance of the Class. To create an object, we use the Class name followed by parentheses.
If the Class has a no-argument constructor, we can instantiate the Class without passing any arguments. The object is created and assigned to a variable.
We can then access the data members and member functions of the object using the dot notation. class Class_Name:
data_member_1 = value_1
data_member_2 = value_2
def member_function_1(self, parameter_1):
# code block
return output
# Instantiate Class_Name using the no-argument constructor
object_name = Class_Name()
# Access data members of the object
print(object_name.data_member_1)
print(object_name.data_member_2)
# Call member functions of the object
output = object_name.member_function_1(parameter_1)
In the above example, we can see that an object of the Class Class_Name is instantiated using the no-argument constructor.
We can access the data members of the object using the dot notation. We can also call the member functions of the object by passing the necessary arguments.
Conclusion
In conclusion, Object Oriented Programming is a powerful programming paradigm that allows for the creation of reusable components called objects. Python is a popular programming language that supports OOP, and classes and objects are the foundation of OOP in Python.
By defining a Class and instantiating it to create an object, we can use the full potential of OOP to create modular, manageable, and reusable code.
3) Class Objects
Object Definition:
In Object-Oriented Programming, an object is an instance of a class that defines properties and methods. An object has a unique identity, state, and behavior.
The identity of an object is a unique identifier that distinguishes it from other objects. The state of an object is defined by its data members, and the behavior of an object is defined by its member functions.
Base Class in Python:
A Base Class is a class that other classes inherit from. In Python, all classes must inherit from the object class, which is the base class for all classes in Python.
Inheritance allows us to create a hierarchy of classes and reuse code between classes. Defining a Constructor for the Class:
The constructor is a special member function that gets called when an object is created.
In Python, the constructor is defined using the __init__ method. The __init__ method is called with the keyword ‘self’ as the first parameter, followed by any additional parameters that the constructor requires.
Within the constructor, we can define the data members of the object and perform any necessary initialization. Example – Defining a constructor for the Employee class:
“`class Employee:
def __init__(self, name, age, salary):
self.name = name
self.age = age
self.salary = salary“`
In the above example, the constructor of the Employee class takes three parameters: name, age, and salary.
These parameters are used to initialize the name, age, and salary data members of the Employee class object.
Multiple Constructors in Python:
Python does not support method overloading, which means we cannot define multiple methods with the same name in a single class.
However, we can use default arguments to simulate method overloading and define multiple constructors for a class. Example – Defining multiple constructors for the Employee class:
“`class Employee:
def __init__(self, name, age, salary):
self.name = name
self.age = age
self.salary = salary
def __init__(self, name, age):
self.name = name
self.age = age
self.salary = None“`
In the above example, we have defined two constructors for the Employee class.
The first constructor takes three parameters: name, age, and salary. The second constructor takes two parameters: name and age.
If the second constructor is called, the salary data member is set to None by default.
4) Class Variables vs Instance Variables
Variables Definition:
A variable is a storage location in a program that holds a value. In Python, variables can be defined at the class level or the instance level.
Class Variables:
Class variables are variables that are shared by all instances of a class. They are defined at the class level, outside of any methods.
Class variables are accessed using the class name, rather than an instance of the class. Modifying a class variable affects all instances of the class.
Example – Defining a class variable in the Employee class:
“`class Employee:
count = 0 #class variable
def __init__(self, name, age, salary):
self.name = name
self.age = age
self.salary = salary
Employee.count += 1“`
In the above example, we have defined a class variable named count in the Employee class. The count variable is initialized to 0, and every time a new instance of the Employee class is created, the count variable is incremented by 1.
The count variable is accessed using the Employee class name, rather than an instance of the class. Instance Variables:
Instance variables are variables that are unique to each instance of a class.
They are defined inside the constructor of the class. Instance variables are accessed using an instance of the class.
Modifying an instance variable affects only the instance it belongs to. Example – Defining an instance variable in the Employee class:
“`class Employee:
def __init__(self, name, age, salary):
self.name = name #instance variable
self.age = age #instance variable
self.salary = salary #instance variable“`
In the above example, we have defined three instance variables in the Employee class: name, age, and salary.
Each instance of the Employee class will have its own set of these instance variables, and they can be accessed using an instance of the class.
Conclusion:
In Object-Oriented Programming,
Classes and Objects are the fundamental building blocks. In Python, classes are defined using the class reserved keyword, and objects are created using the class name and parentheses.
A constructor is a special method that is called when an object is created, and it is used to initialize the data members of the object. Class variables and instance variables are two types of variables that define the properties of the object.
Class variables are shared by all instances of the class, while instance variables are unique to each instance of the class. Understanding these concepts is essential to creating efficient and maintainable code in Python.
5) Summary of Object Oriented Programming in Python
Object-Oriented Programming (OOP) is a programming paradigm that is used to model real-world objects as software objects. OOP is based on four fundamental principles: Polymorphism, Encapsulation, Inheritance, and Data Abstraction.
Python, a high-level programming language, supports OOP and provides various features that make programming in OOP easy and efficient. Definition of Object-Oriented Programming:
OOP is a programming paradigm based on the concept of Objects.
An Object is a software entity with a unique identity, state, and behavior. OOP is designed to reduce redundancy in code and make it easier to maintain and manage.
Polymorphism:
Polymorphism is the ability of an object to take on many forms. In Python, this is achieved through a process called Method Overriding.
Method Overriding is the process of providing a different implementation of a method from the base class in the derived class. Encapsulation:
Encapsulation is the process of hiding the implementation details of an object from the outside world.
In Python, this is achieved through the use of data members and member functions defined in a Class. By encapsulating an object’s data and methods, we can prevent accidental modification of data and ensure that the object is used according to its intended purpose.
Inheritance:
Inheritance is the process of creating a new class from an existing class. Inheritance allows us to reuse code from existing classes and create a new class with extended functionality.
In Python, all classes inherit from the object class. Data Abstraction:
Data Abstraction is the process of simplifying complex data by hiding unnecessary details.
In Python, data abstraction is achieved through the use of abstract classes and abstract methods. An abstract class is a class that cannot be instantiated and contains at least one abstract method that must be overridden in the derived class.
Importance of Object-Oriented Programming:
Object-Oriented Programming is important because it allows us to create stable, scalable, and maintainable code. By encapsulating objects and data, we can ensure that they are used correctly and prevent accidental modification of data.
Inheritance allows us to reuse code and create new classes with extended functionality. Polymorphism allows us to write generic functions that work with objects of different types.
Class and Objects:
Classes and objects are the foundation of Object-Oriented Programming. Classes define the properties and behavior of an object, while objects are the instances of a Class.
By defining Classes and creating objects, we can write efficient and maintainable code that is easy to read and debug.
Conclusion:
In conclusion, Object-Oriented Programming is an essential programming paradigm in modern software development. Python, a popular programming language, provides various features that support OOP, making it easier to write efficient and maintainable code.
By understanding the fundamental principles of OOP, including Polymorphism, Encapsulation, Inheritance, and Data Abstraction, and by using
Classes and Objects, we can write code that is scalable, maintainable, and easy to understand. In summary, Object-Oriented Programming (OOP) is a fundamental programming paradigm that enables software objects to model real-world objects.
Python, as a high-level programming language, offers various features that make OOP more efficient. OOP helps reduce redundancy in code, improve scalability, and ensure stability and maintainability.
Important OOP principles in Python include Polymorphism, Encapsulation, Inheritance, and Data Abstraction, while
Classes and Objects serve as the backbone. Embracing best practices, such as understanding OOP basics and effectively using
Classes and Objects, enable one to write scalable and maintainable code.
Therefore, it is important to master OOP in Python to succeed in software development.