Classes & Objects

# Define a class
class Dog:
    # Class attribute (shared by all instances)
    species = "Canis familiaris"
    
    # Constructor (__init__)
    def __init__(self, name, age):
        # Instance attributes (unique to each object)
        self.name = name
        self.age = age
    
    # Instance method
    def bark(self):
        return f"{self.name} says Woof!"
    
    def info(self):
        return f"{self.name} is {self.age} years old"

# Create objects (instances)
dog1 = Dog("Rex", 5)
dog2 = Dog("Buddy", 3)

print(dog1.bark())   # Rex says Woof!
print(dog2.info())   # Buddy is 3 years old
print(dog1.species)  # Canis familiaris

# Modify attributes
dog1.age = 6
print(f"{dog1.name} is now {dog1.age}")

# isinstance check
print(isinstance(dog1, Dog))  # True