Object-Oriented

Attributes→data Methods→function

Class and objects:

class Dog:
	def __init__(self,name,breed):
		self.name = name
		self.breed=breed
	def bark(self):
		print(f"{self.name} says Woof!")
dog1=Dog("Buddy","Golden Retriever")
dog1.bark()

init acts like constructor self is like “this” which indicated the currently instance of class.

It support Encapsulation which is hiding the internal state of an object and only exposes what necessary It also support Abstraction which means hiding complex logic and show only important features It also support Polymorphism which means same interface,different behaviour .Achieved via method overriding or duck typing

Some extra concepts

super() keyword: Used to call the parent class constructor or methods.

class Parent:
    def __init__(self):
        print("Parent initialized")
 
class Child(Parent):
    def __init__(self):
        super().__init__()  # call parent constructor
        print("Child initialized")
 
child = Child()

😂

Afno papa lai bolaunxa

Class Methods and Static Methods:

Class method:

• Takes cls as the first argument
• Works with the class itself, not the object
• Can be used to create alternative constructors -Static method:- No self or cls required
• Behaves like a regular function inside a class
• Used when the method does not need access to class or instance data

python

Copy code

class Math:
    @staticmethod
    def add(x, y):
        return x + y
 
    @classmethod
    def info(cls):
        return "This is a Math class"
 
print(Math.add(5, 3))
print(Math.info())
 

__str__ and __repr__

str:User friendly display Called by print(obj) or str(obj) repr:Developer/debug-friendly display

class Book:
    def __init__(self, title, price):
        self.title = title
        self.price = price
 
    def __str__(self):
        return f"'{self.title}' costs Rs. {self.price}"
 
    def __repr__(self):
        return f"Book(title='{self.title}', price={self.price})"
book = Book("Python 101", 500)
 
print(book)         # 👉 calls __str__
print(str(book))    # 👉 also calls __str__
 
print(repr(book))   # 👉 calls __repr__
book                # 👉 REPL (console) uses __repr__