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Classes and Objects: Introduction to Classes and Objects

Understanding Classes

Title Concept Description
Definition of Classes Classes are blueprints for creating objects in Python. Define attributes and methods common to all instances of the class.
Purpose of Classes Encapsulation, Inheritance, Polymorphism. Encapsulate data and behavior, promote code reuse, allow flexible method implementations.
Difference Between Class and Object Class is a template; object is an instance of the class. Classes define attributes and methods; objects have specific attribute values.

Basics of Object-Oriented Programming

Title Concept Description
Encapsulation Bundling data and methods within a class to restrict direct access. Enhances data protection and code modularity.
Inheritance Creating new classes based on existing ones. Promotes code reuse and establishes class hierarchies.
Polymorphism Treating objects of different classes as objects of a common superclass. Allows for flexible and reusable code.
Advantages of OOP in Python Code Reusability, Modularity, Flexibility, Maintainability. Enhances code structure and efficiency.

Classes and Objects: Creating Classes in Python

1. Class Declaration

Title Concept Code
Syntax for Declaring Classes Define a class using the class keyword. 
class ClassName:
    # Class attributes and methods go here
Naming Conventions Use CamelCase for class names. For example, class Car:

2. Attributes and Methods

Title Concept Code
Defining Attributes Variables holding data associated with objects. 
class Dog:
    def init(self, name, age):
        self.name = name
        self.age = age
Creating Methods Functions within a class for operations on attributes. 
class Circle:
    def init(self, radius):
        self.radius = radius
    def calculate_area(self):
        return 3.14 * self.radius ** 2

3. Constructor Method

Title Concept Code
Definition and Usage of Constructors Special method initializing new objects. 
class Person:
    def init(self, name, age):
        self.name = name
        self.age = age
Role of Special Method __init__ Sets the initial state of objects. 
person1 = Person("Alice", 30)
# person1.name will be "Alice" and person1.age will be 30

Instance and Class Variables

1. Instance Variables

Title Concept Code
Definition and Scope of Instance Variables Unique to each object of a class. 
class Car:
    def init(self, brand, model):
        self.brand = brand
        self.model = model
my_car = Car("Toyota", "Camry")
print(my_car.brand)  # Output: Toyota
Setting and Accessing Instance-Specific Data Use self keyword within class methods. 
class Student:
    def init(self, name, age):
        self.name = name
        self.age = age
    def display_info(self):
        print(f"Name: {self.name}, Age: {self.age}")
student = Student("Alice", 20)
student.display_info()

2. Class Variables

Title Concept Code
Understanding Class-Level Variables Shared among all instances of a class. 
class Circle:
    pi = 3.14
    def init(self, radius):
        self.radius = radius
    def calculate_area(self):
        return Circle.pi * self.radius ** 2
circle = Circle(5)
print(circle.calculate_area())  # Output: 78.5
Accessing and Modifying Class Variables Use the class name to access or modify them. 
class BankAccount:
    interest_rate = 0.05
account = BankAccount()
print(account.interest_rate)  # Output: 0.05
BankAccount.interest_rate = 0.06
print(account.interest_rate)  # Output: 0.06

Classes and Objects: Inheritance in Python

Inheritance in Python

Title Concept Description
Definition and Purpose of Inheritance Derive new classes from existing ones. Promotes code reuse and extends base class functionality.
Types of Inheritance Single, Multiple, Multilevel, Hierarchical. Inherit attributes and methods in various ways.

Syntax for Inheriting Classes

Title Concept Code
Extending Base Classes Specify the base class for inheritance. 
class BaseClass:
    def show(self):
        print("Base Class method")
class SubClass(BaseClass):
    def show(self):
        print("SubClass method")
# Creating objects and calling methods
base_obj = BaseClass()
sub_obj = SubClass()
base_obj.show()  # Output: Base Class method
sub_obj.show()   # Output: SubClass method
Overriding Methods in Subclasses Define a method with the same name in the subclass. Customize behavior specific to the subclass.

super() Method

Title Concept Code
Utilization of super() for Method Resolution Invoke methods from the base class. 
class BaseClass:
    def show(self):
        print("Base Class method")
class SubClass(BaseClass):
    def show(self):
        super().show()
        print("SubClass method")
sub_obj = SubClass()
sub_obj.show()
# Output:
# Base Class method
# SubClass method
Benefits of super() in Resolving Inheritance Conflicts Ensures proper method resolution and simplifies structure. Useful in multiple inheritance scenarios.

Classes and Objects: Polymorphism and Method Overriding

Polymorphism and Method Overriding

Polymorphism

Title Concept Description
Understanding Polymorphism Treat objects of different classes as a common superclass. Enhances code structure and flexibility.
Advantages of Polymorphism Code Reusability and Enhanced Flexibility. Use shared method names with distinct implementations.

Method Overriding

Title Concept Code
Definition of Method Overriding Subclass provides specific method implementation. Customize inherited methods for subclass needs.
Implementing Method Overriding Define a method with the same name in the subclass. 
class Animal:
    def sound(self):
        print("Animal makes a sound")
class Dog(Animal):
    def sound(self):
        print("Dog barks")
class Cat(Animal):
    def sound(self):
        print("Cat meows")
dog = Dog()
dog.sound()  # Output: Dog barks
cat = Cat()
cat.sound()  # Output: Cat meows

Classes and Objects: Encapsulation and Data Hiding

Encapsulation

Title Concept Description
Encapsulation Concept Bundle data and methods in a class to control access. Enhances organization and safeguards object integrity.
Purpose and Benefits of Encapsulation Data Protection, Modularity, Flexibility. Control data access, improve organization, enhance maintainability.
Implementing Encapsulation in Python Classes Use private attributes and public methods. 
class BankAccount:
    def init(self, initial_balance):
        self.__balance = initial_balance<br