Object-Oriented Programming in Python

class Person:
    def __init__(self, name, age):
        self.name = name
        self.age = age

    def greet(self):
        return f"Hi, I'm {self.name}, {self.age} years old."

# Instantiate and use
p = Person("Alice", 30)
print(p.greet())  # Hi, I'm Alice, 30 years old.
 

class Employee(Person):
    def __init__(self, name, age, role):
        super().__init__(name, age)
        self.role = role

    def greet(self):
        base = super().greet()
        return f"{base} I work as a {self.role}."

e = Employee("Bob", 28, "Developer")
print(e.greet())  # Hi, I'm Bob, 28 years old. I work as a Developer.
 

class Account:
    def __init__(self, balance=0):
        self.__balance = balance

    @property
    def balance(self):
        return self.__balance

    def deposit(self, amount):
        if amount > 0:
            self.__balance += amount

acct = Account(100)
print(acct.balance)  # 100
# acct.__balance  # AttributeError
 

class Dog:
    def speak(self):
        return "Woof!"

class Cat:
    def speak(self):
        return "Meow!"

for animal in (Dog(), Cat()):
    print(animal.speak())  # Woof! Meow!
 

class Vector:
    def __init__(self, x, y):
        self.x, self.y = x, y

    def __add__(self, other):
        return Vector(self.x + other.x, self.y + other.y)

    def __repr__(self):
        return f"Vector({self.x}, {self.y})"

v1, v2 = Vector(1, 2), Vector(3, 4)
print(v1 + v2)  # Vector(4, 6)