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@author jackzhenguo
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@date 2020/02/04

137 统计异常次数装饰器

写一个装饰器,统计某个异常重复出现指定次数时,经历的时长。

import time
import math


def excepter(f):
    i = 0
    t1 = time.time()
    def wrapper(): 
        try:
            f()
        except Exception as e:
            nonlocal i
            i += 1
            print(f'{e.args[0]}: {i}')
            t2 = time.time()
            if i == n:
                print(f'spending time:{round(t2-t1,2)}')
    return wrapper

关键词nonlocal常用于函数嵌套中,声明变量i为非局部变量;

如果不声明,i+=1表明i为函数wrapper内的局部变量,因为在i+=1引用(reference)时,i未被声明,所以会报unreferenced variable的错误。

使用创建的装饰函数excepter, n是异常出现的次数。

共测试了两类常见的异常:被零除数组越界

n = 10 # except count

@excepter
def divide_zero_except():
    time.sleep(0.1)
    j = 1/(40-20*2)

# test zero divived except
for _ in range(n):
    divide_zero_except()


@excepter
def outof_range_except():
    a = [1,3,5]
    time.sleep(0.1)
    print(a[3])
# test out of range except
for _ in range(n):
    outof_range_except()

打印出来的结果如下:

division by zero: 1
division by zero: 2
division by zero: 3
division by zero: 4
division by zero: 5
division by zero: 6
division by zero: 7
division by zero: 8
division by zero: 9
division by zero: 10
spending time:1.01
list index out of range: 1
list index out of range: 2
list index out of range: 3
list index out of range: 4
list index out of range: 5
list index out of range: 6
list index out of range: 7
list index out of range: 8
list index out of range: 9
list index out of range: 10
spending time:1.01

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