First touch with python decorator

Question

I am getting familiar with decorators, and after a couple of tutorials i came up with a decorator that might is useful for me. Is this the proper way to use decorators? Any suggestion about the code?

def timeit_decorator(original_function):
 import time
 import colorama
 def wrapper(*args, **kwargs):
 tm = time.time()
 res = original_function(*args, **kwargs)
 print("Function " + colorama.Fore.GREEN + original_function.__name__ + colorama.Style.RESET_ALL + " executed in " + colorama.Fore.GREEN + "~{:.2f}".format(
 (time.time() - tm) / 60) + colorama.Style.RESET_ALL + " minutes!")
 return res
 return wrapper

Example of usage:

@timeit_decorator
def display(msg):
 time.sleep(10)
 return msg
print(display(1))

Answer 1

When using decorators, you should familiarize yourself with functools.wraps. Consider the difference in available informations between these two (useless) decorators:

from functools import wraps
def decorate1(func):
 def wrapper(*args, **kwargs):
 return func(*args, **kwargs)
 return wrapper
def decorate2(func):
 @wraps(func)
 def wrapper(*args, **kwargs):
 return func(*args, **kwargs)
 return wrapper

When applied to a function:

@decorate1
def test1(x, y, z):
 "test1 docstring"
 print(x, y, z)
@decorate2
def test2(x, y, z):
 "test2 docstring"
 print(x, y, z)

The help on each function look quite different:

>>> help(test1)
Help on function wrapper in module __main__:
wrapper(*args, **kwargs)
>>> help(test2)
Help on function test2 in module __main__:
test2(x, y, z)
 test2 docstring

---

Since you’re using Python 3, you should consider using better timing primitives. Namely time.perf_counter():

def wrapper(*args, **kwargs):
 begin = time.perf_counter()
 res = original_function(*args, **kwargs)
 elapsed = time.perf_counter() - begin

---

Lastly, you should consider using format all along instead of string concatenation:

import time
import colorama
from functools import wraps
def timeit_decorator(original_function):
 @wraps(original_function)
 def wrapper(*args, **kwargs):
 begin = time.perf_counter()
 result = original_function(*args, **kwargs)
 elapsed = time.perf_counter() - begin
 print("Function {color}{}{reset} executed in {color}"
 "~{:.2f}{reset} minutes!"
 .format(
 original_function.__name__,
 elapsed / 60,
 color=colorama.Fore.GREEN,
 reset=colorama.Style.RESET_ALL))
 return result
 return wrapper

• Gábor Erdős: Thanks a lot for the long answer, it was really helpful!