Chapter 7: Object-Oriented Programming (OOP)

7.1 Introduction to
Object-Oriented Programming 7.1.1 Objects, classes, and attributes Explanation:
Object-oriented programming focuses on creating objects that encapsulate data
and behavior. Objects are instances of classes, which define their attributes (data)
and methods (behavior). Example:

python

///Example

class Person:

    def __init__(self, name, age):

        self.name = name

        self.age = age

 

    def greet(self):

        print("Hello, my name is",
self.name)

 

person1 =
Person("Alice", 25)

person1.greet()

 

7.1.2 Encapsulation,
inheritance, and polymorphism Explanation: OOP concepts include encapsulation
(data hiding), inheritance (creating new classes from existing ones), and
polymorphism (objects of different classes can be treated interchangeably).
Example:

python

///Example

class Shape:

    def area(self):

        pass

 

class Rectangle(Shape):

    def __init__(self, width, height):

        self.width = width

        self.height = height

 

    def area(self):

        return self.width * self.height

 

class Circle(Shape):

    def __init__(self, radius):

        self.radius = radius

 

    def area(self):

        return 3.14 * self.radius ** 2

 

shapes = [Rectangle(4,
5), Circle(3)]

for shape in shapes:

    print("Area:", shape.area())

 

7.2 Classes and Objects
7.2.1 Defining classes and creating objects Explanation: Classes are defined
using the class keyword and can have attributes and methods. Objects are
created by instantiating a class using the class name followed by parentheses.
Example:

python

///Example

class Car:

    def __init__(self, brand, model):

        self.brand = brand

        self.model = model

 

    def drive(self):

        print("Driving", self.brand,
self.model)

 

car1 =
Car("Toyota", "Corolla")

car1.drive()

 

7.2.2 Class attributes
and instance attributes Explanation: Class attributes are shared by all
instances of a class, while instance attributes are specific to each instance.
Class attributes are defined outside of any methods. Example:

python

///Example

class Dog:

    species = "Canine"  # Class attribute

 

    def __init__(self, name):

        self.name = name  # Instance attribute

 

dog1 =
Dog("Max")

print(dog1.name)  # Instance attribute

print(dog1.species)  # Class attribute

 

7.2.3 Class methods and
static methods Explanation: Class methods are defined using the @classmethod
decorator and can access class-level data. Static methods are defined using the
@staticmethod decorator and don't have access to instance or class data.
Example:

python

///Example

class MathUtils:

    @classmethod

    def add(cls, a, b):

        return a + b

 

    @staticmethod

    def multiply(a, b):

        return a * b

 

result1 =
MathUtils.add(2, 3)  # Class method

result2 =
MathUtils.multiply(4, 5)  # Static method

print(result1)

print(result2)

 

7.3 Inheritance and
Polymorphism 7.3.1 Inheriting from a superclass Explanation: Inheritance allows
you to create new classes (subclasses) based on existing ones (superclasses).
Subclasses inherit attributes and methods from their superclasses. Example:

python

///Example

class Animal:

    def make_sound(self):

        pass

 

class Dog(Animal):

    def make_sound(self):

        print("Woof!")

 

dog1 = Dog()

dog1.make_sound()

 

7.3.2 Overriding
methods in subclasses Explanation: Subclasses can override methods inherited
from superclasses by providing a new implementation. The overridden method in
the subclass is used instead of the superclass method. Example:

python

///Example

class Animal:

    def make_sound(self):

        print("Generic animal sound")

 

class Dog(Animal):

    def make_sound(self):

        print("Woof!")

 

animal1 = Animal()

animal1.make_sound()  # Generic animal sound

 

dog1 = Dog()

dog1.make_sound()  # Woof!

 

7.3.3 Polymorphism and
method overriding Explanation: Polymorphism allows objects of different classes
to be treated interchangeably. Method overriding enables subclasses to provide
their own implementation of inherited methods. Example:

python

///Example

class Shape:

    def area(self):

        pass

 

class Rectangle(Shape):

    def __init__(self, width, height):

        self.width = width

        self.height = height

 

    def area(self):

        return self.width * self.height

 

class Circle(Shape):

    def __init__(self, radius):

        self.radius = radius

 

    def area(self):

        return 3.14 * self.radius ** 2

 

shapes = [Rectangle(4,
5), Circle(3)]

for shape in shapes:

    print("Area:", shape.area())

 

This chapter covers the
fundamental concepts of object-oriented programming (OOP). OOP allows you to
create classes and objects, define attributes and methods, and leverage
inheritance and polymorphism for code reuse and flexibility. The examples
provided demonstrate the usage and syntax of each topic, helping readers
understand how to apply these concepts in their own programs.