Python Decorators

Understand the idea

The @ syntax passes the function into the decorator and binds the returned callable to its name. functools.wraps preserves helpful metadata such as the original name and docstring. Forward *args and **kwargs correctly, return the wrapped result, and do not swallow exceptions unless handling them is part of the documented policy.

Where to try it

Open this example with Try in playground. The code loads as editable text and does not run until you select Run. The first run downloads Python. Each run starts fresh; temporary files created by a script are not files on your PC.

A worked example

from functools import wraps
def announce(function):
    @wraps(function)
    def wrapper(*args, **kwargs):
        print("Starting", function.__name__)
        return function(*args, **kwargs)
    return wrapper

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

print(add(2, 3))

Read the result

The output announces add and then prints 5. The wrapper returns the calculation rather than replacing it with None.

Try one change

Decorate another function taking a keyword argument and verify that its result and name are preserved.