1. Introduction to OOP
- Object-Oriented Programming (OOP) is a programming paradigm based on the concept of objects, which can contain data (attributes) and methods (functions).
- Benefits of OOP:
- Code reusability through inheritance.
- Better organization with encapsulation.
- Enhanced functionality using polymorphism.
2. Key OOP Concepts in Python
- Class: Blueprint for creating objects.
- Object: Instance of a class.
- Attributes: Variables that belong to an object.
- Methods: Functions that belong to a class.
3. Defining Classes and Creating Objects
- Example of a class:pythonCopy code
Python
class Car:
def __init__(self, brand, model):
self.brand = brand
self.model = model
def display_info(self):
print(f"Car: {self.brand} {self.model}")
# Creating an object
my_car = Car("Toyota", "Corolla")
my_car.display_info()
4. The __init__ Method
- Special method called a constructor, used for initializing object attributes.
- Example:
Python
class Person:
def __init__(self, name, age):
self.name = name
self.age = age
def greet(self):
print(f"Hello, my name is {self.name}.")
p1 = Person("Alice", 25)
p1.greet()
5. Inheritance
- A mechanism to create a new class (child class) based on an existing class (parent class).
- Example:
Python
class Animal:
def speak(self):
print("Animal speaks.")
class Dog(Animal):
def speak(self):
print("Dog barks.")
my_dog = Dog()
my_dog.speak() # Output: Dog barks.
6. Encapsulation
- Restricts access to certain attributes or methods to prevent unauthorized modifications.
- Use underscores
_or__to define private attributes.pythonCopy code
Python
class BankAccount:
def __init__(self, balance):
self.__balance = balance
def get_balance(self):
return self.__balance
account = BankAccount(1000)
print(account.get_balance()) # Output: 1000
7. Polymorphism
- The ability of different classes to be treated as instances of the same class through shared methods.
- Example
Python
class Bird:
def fly(self):
print("Bird is flying.")
class Penguin(Bird):
def fly(self):
print("Penguins can't fly.")
for bird in [Bird(), Penguin()]:
bird.fly()
8. Working with super()
- The
super()function allows access to the methods of the parent class.
Python
class Vehicle:
def __init__(self, brand):
self.brand = brand
class Bike(Vehicle):
def __init__(self, brand, model):
super().__init__(brand)
self.model = model
9. Special (Magic) Methods
- Python provides special methods like
__str__,__repr__, and more
Python
class Book:
def __init__(self, title, author):
self.title = title
self.author = author
def __str__(self):
return f"{self.title} by {self.author}"
book = Book("1984", "George Orwell")
print(book) # Output: 1984 by George Orwell