problem In using functools in a code

[akbarza]

hi
in code:

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# from: https://python.coderz.ir/lessons/l13-decorator-generator-and-lambda-with-python-functions.html import functools import time   def timer(func):     """Print the runtime of the decorated function"""     #     @functools.wraps(func)     #     def wrapper_timer(*args, **kwargs):          start_time = time.perf_counter()          value = func(*args, **kwargs)          end_time = time.perf_counter()          run_time = end_time - start_time          print(f"Finished {func.__name__!r} in {run_time:.4f} secs")          return value     return wrapper_timer     @timer def waste_some_time(num_times):      """This function only wastes some times."""      result = 0      for _ in range(num_times):          for i in range(10000):              result += i**2   if __name__=="__main__" :     print(f" result of running command 'waste_some_time(1)' is :")     waste_some_time(1)     print()     print(f" result of running command 'waste_some_time(999)' is :")     waste_some_time(999)     print(f"result of command 'waste_some_time.__name__' is: \ {waste_some_time.__name__}")     print(f"result of  command 'waste_some_time.__doc__' is: \ {waste_some_time.__doc__}")

when a module is imported, for using its function, only the function is called. for example, I write:

1 2	import math math.exp(1)

but in line 8 of the above code, there is @ functools.wraps(func). why this @is used for? I read about wraps a little value, but I did not understand it. for what we use this?
thanks

[Gribouillis]

It is all explained in the documentation of functools.wraps() and functools.update_wrapper(). Have you read it?

[akbarza]

It is all explained in the documentation of functools.wraps() and functools.update_wrapper(). Have you read it?

hi
I did not see them, i will try read them.
thanks

[buran]

why this @is used for?

are you asking about decorators in principle or about this specific one?

[akbarza]

why this @is used for?

are you asking about decorators in principle or about this specific one?

i asked about@ sign in line 8.

[buran]

This (the @) is used for decorator syntax

check
https://peps.python.org/pep-0318/
https://realpython.com/primer-on-python-decorators/

[akbarza]

This (the @) is used for decorator syntax

check
https://peps.python.org/pep-0318/
https://realpython.com/primer-on-python-decorators/

hi
as you can see the timer, itself is a decorator and you say @functools.wraps(func) is a decorator again, namely decorator inside decorator?

[DeaD_EyE]

Decorator means, there is a function, which takes a function and return a new function.
functools.wraps is a wrapper, and it copies from the original function the docstring, call-specs and some other stuff to the inner function. This is better for debugging.

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def debug(func):     def inner():         print("Running func")         result = func()         print("Done")         return result     return inner     def test1():     print("Hello")   test1 = debug(test1) result = test1()   # The same with syntactical sugar @debug def test2():     print("Hello")     test2()