Decorators

Detailed answer

A parameterized decorator is a function returning a decorator. Use functools.wraps to preserve metadata. For async functions, detect coroutines and await inside the wrapper.

Code example

import functools, time

def timed(label: str):
    def deco(fn):
        @functools.wraps(fn)
        def wrapper(*args, **kwargs):
            start = time.perf_counter()
            try:
                return fn(*args, **kwargs)
            finally:
                print(f"{label}: {time.perf_counter()-start:.4f}s")
        return wrapper
    return deco

Practice code · python (view only · no execution)

import functools, time

def timed(label: str):
    def deco(fn):
        @functools.wraps(fn)
        def wrapper(*args, **kwargs):
            start = time.perf_counter()
            try:
                return fn(*args, **kwargs)
            finally:
                print(f"{label}: {time.perf_counter()-start:.4f}s")
        return wrapper
    return deco