Decorators in Python

Hey there! In this guide, we'll explore decorators in Python. Decorators are a powerful and flexible way to modify the behavior of functions or methods. They allow you to add functionality to existing code in a clean and readable way. Let's dive in!

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Python Decorators

• Function Modification: Decorators allow you to extend or modify the behavior of functions or methods without changing their code.
• Higher-Order Functions: Decorators are often implemented as higher-order functions, meaning they take another function as an argument.

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1. Defining a Simple Decorator

You can define a simple decorator by creating a function that takes another function as an argument and returns a new function.

def my_decorator(func):
    def wrapper():
        print("Something is happening before the function is called.")
        func()
        print("Something is happening after the function is called.")
    return wrapper

2. Applying a Decorator

You can apply a decorator to a function using the @decorator_name syntax above the function definition.

@my_decorator
def say_hello():
    print("Hello!")

say_hello()  # Output:
# Something is happening before the function is called.
# Hello!
# Something is happening after the function is called.

3. Decorators with Arguments

You can create decorators that accept arguments by defining another level of nested functions.

def repeat(num_times):
    def decorator_repeat(func):
        def wrapper(*args, **kwargs):
            for _ in range(num_times):
                func(*args, **kwargs)
        return wrapper
    return decorator_repeat

@repeat(3)
def greet(name):
    print(f"Hello, {name}!")

greet("Alice")  # Output:
# Hello, Alice!
# Hello, Alice!
# Hello, Alice!

4. Using functools.wraps

When creating decorators, it's a good practice to use functools.wraps to preserve the original function's metadata.

from functools import wraps

def my_decorator(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        print("Something is happening before the function is called.")
        return func(*args, **kwargs)
    return wrapper

@my_decorator
def say_hello():
    """This function says hello."""
    print("Hello!")

print(say_hello.__name__)  # Output: say_hello
print(say_hello.__doc__)   # Output: This function says hello.

5. Chaining Decorators

You can apply multiple decorators to a single function by stacking them.

def decorator_one(func):
    def wrapper():
        print("Decorator One")
        func()
    return wrapper

def decorator_two(func):
    def wrapper():
        print("Decorator Two")
        func()
    return wrapper

@decorator_one
@decorator_two
def say_hello():
    print("Hello!")

say_hello()  # Output:
# Decorator One
# Decorator Two
# Hello!