Python Decorator

利用装饰器记录函数运行时间

import datetime
import time
from functools import reduce

class Decorator():
    @staticmethod
    def exectime(func):
        def decor(*arg):
            start = datetime.datetime.now()
            ret = func(*arg)
            print("{} = {}".format(func.__name__, ret))
            end = datetime.datetime.now()
            interval = end - start
            print("{} execution time: {}".format(func.__name__, interval))
            return ret      
        return decor

class Util():
    @staticmethod
    # @Decorator.exectime
    def sum(*arg):
        # slotion 1
        # s=0
        # for i in arg:
        #     # time.sleep(1)
        #     s+=i

        # solution 2
        # head, *remain = arg
        # if remain is None:
        #     return 0
        # return header + sum(remain)
        
        # solution 3
        return reduce(lambda x,y:x+y, arg)
Util.sum(1,2,3)

>> sum = 6
>> sum execution time: 0:00:03.012014

list去空
s=['A', '', 'B', None, 'C', ' ']
s=list(filter(lambda x:x and x.strip(), s))

if x and y or z 等于三元表达式 x?y:z