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Python Classes

·285 words·2 mins·
Programming Python Classes Oop Programming
Table of Contents

Python Classes
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Classes provide a means of bundling data and functionality together. Creating a new class creates a new type of object, allowing new instances of that type to be made.

Defining a Class
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You can define a class using the class keyword.

class Dog:
    # Class attribute
    species = "Canis familiaris"

    # Initializer / Instance attributes
    def __init__(self, name, age):
        self.name = name
        self.age = age

    # Instance method
    def description(self):
        return f"{self.name} is {self.age} years old"

    # Another instance method
    def speak(self, sound):
        return f"{self.name} says {sound}"

Creating an Instance
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To create an instance of a class, you call the class as if it were a function.

# Create an instance of the Dog class
my_dog = Dog("Buddy", 5)

# Access instance attributes
print(my_dog.name)  # Buddy
print(my_dog.age)   # 5

# Call instance methods
print(my_dog.description())  # Buddy is 5 years old
print(my_dog.speak("Woof"))  # Buddy says Woof

Inheritance
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Inheritance allows you to create a new class that inherits the attributes and methods of an existing class.

class Bulldog(Dog):
    def speak(self, sound="Arf"):
        return f"{self.name} says {sound}"

my_bulldog = Bulldog("Rocky", 3)
print(my_bulldog.description())  # Rocky is 3 years old
print(my_bulldog.speak())        # Rocky says Arf

Special Methods
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Classes in Python can implement special methods (also known as “dunder” methods) that begin and end with double underscores. These methods allow you to customize the behavior of your objects.

  • __init__: The constructor for the class.
  • __str__: Returns a string representation of the object.
  • __len__: Returns the length of the object.
  • __repr__: Returns an official string representation of the object.
class Car:
    def __init__(self, make, model):
        self.make = make
        self.model = model

    def __str__(self):
        return f"A {self.make} {self.model}"

my_car = Car("Toyota", "Corolla")
print(my_car)  # A Toyota Corolla

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