修饰器使函数返回无

Question

我建立了两个函数来查找素数因子。一个版本比大数量的其他功能慢。我想评估这两个函数的运行时间。要做到这一点，我建立了一个装饰者来评估黯然失色的时间。 由于我插入装饰器，我的两个函数返回None。我的代码有什么问题？

import math 
import time 

def time_usage(func): 
    def wrapper(*args, **kwargs): 
     beg_ts = time.time() 
     func(*args, **kwargs) 
     end_ts = time.time() 
     print("[INFO] elapsed time: %f" % (end_ts - beg_ts)) 
    return wrapper 

@time_usage 
def find_factors(n): 
    factors = [] 
    i = 2 
    while i < n: 
     while (n % i) == 0: 
      factors.append(i) 
      n /= i 
     i += 1 
    if n > 1: 
     factors.append(n) 
    return factors 

@time_usage 
def improved_prime_factor(n): 
    factors = [] 
    # No need to test whether the number is divisible by any 
    # even number other than 2 
    while n % 2 == 0: 
     factors.append(2) 
     n /= 2 
    i = 3 
    # If n = p * q, either p or q must be <= sqrt(n) 
    max_factor = math.sqrt(n) 
    while i <= max_factor: 
     while n % i == 0: 
      factors.append(i) 
      n /= i 
      # Update the upper band on possible factors 
      max_factor = math.sqrt(n) 
     i += 2 
    if n > 1: 
     factors.append(n) 
    return factors 

if __name__ == '__main__': 
    print(improved_prime_factor(125556)) # return None 
    print(find_factors(125556)) # return None 

Answer 1

您需要退回func(*args, **kwargs)。此外，它是一个很好的做法，与functools.wraps

import functools 


def time_usage(func):  
    @functools.wraps 
    def wrapper(*args, **kwargs): 
     beg_ts = time.time() 
     result = func(*args, **kwargs) # save the result to a name 
     end_ts = time.time() 
     print("[INFO] elapsed time: %f" % (end_ts - beg_ts)) 
     return result # return the name 
    return wrapper