PythonAdvanced

Decorators

Python decorators explained: wrap functions, add behavior, build decorators with arguments, and preserve metadata with functools.wraps.

01Simple decorator

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main.py

def shout(func):
    def wrapper():
        return func().upper()
    return wrapper

@shout
def greet():
    return "hello"

print(greet())

Output

HELLO

02Decorator with arguments

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main.py

def repeat(n):
    def decorator(func):
        def wrapper():
            for _ in range(n):
                func()
        return wrapper
    return decorator

@repeat(3)
def hi():
    print("hi")

hi()

Output

hi
hi
hi

03Preserve metadata with wraps

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main.py

from functools import wraps

def logged(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        print("Calling", func.__name__)
        return func(*args, **kwargs)
    return wrapper

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

print(add(2, 3))

Output

Calling add
5