Introduction to Decorators in Python

Decorators are a powerful and versatile feature in Python that allow you to modify or extend the behavior of functions and methods. They provide a convenient way to add functionality to existing code without modifying its structure. This tutorial will introduce you to the concept of decorators and demonstrate their usage.

What are Decorators?

Decorators in Python are functions that accept another function as input and return a new function as output. They are typically used to modify or wrap the behavior of the input function.

Example:

# Decorator syntax
def my_decorator(func):
    def wrapper():
        print('Before calling the function')
        func()
        print('After calling the function')
    return wrapper

@my_decorator
def say_hello():
    print('Hello, world!')

say_hello()

Output:

Before calling the function
Hello, world!
After calling the function

Common Patterns

Decorators are commonly used for tasks such as logging, authentication, caching, and more. They allow you to separate concerns and keep your code modular and maintainable.

Example:

# Decorator for logging
def log(func):
    def wrapper(*args, **kwargs):
        print(f'Calling function {func.__name__}')
        result = func(*args, **kwargs)
        print(f'Finished calling function {func.__name__}')
        return result
    return wrapper

@log
def add(a, b):
    return a + b

print(add(1, 2))

Output:

Calling function add
Finished calling function add
3

By mastering decorators, you can write more modular and reusable code in Python, improving your codebase's maintainability and flexibility.