python decorator how to add parameters

Question

I have a python decorator, it will round the return of function 2 decimals:

def round_decimal(func):
    def inner(*args, **kwargs):
        return round(func(*args, **kwargs),2)
    return inner

@round_decimal
def func(a,b,c):
    
    return a/b/c

func(1.33333,3.44444,4.555)

The output is:

0.08

My question is how can I make the round decimal a parameters:

Something like this:

def round_decimal(func,decimal):
    def inner(*args, **kwargs):
        return round(func(*args, **kwargs),decimal)
    return inner

@round_decimal(3)
def func(a,b,c):

    return a/b/c

func(1.33333,3.44444,4.555)

if the round decimal equals 3 the output should be:

0.085

Answer 1

You need a decorator factory, that is a function that returns the decorator:

from functools import wraps


def round_decimal(n):
    def decorator(fn):
        @wraps(fn)
        def inner(*args, **kwargs):
            return round(fn(*args, **kwargs), n)

        return inner

    return decorator


@round_decimal(3)
def func(a, b, c):
    return a / b / c


print(func(1.33333, 3.44444, 4.555))

output:

0.085