python基础（三）装饰器

字典推导式：

data_list = ['1 hello','2 world']
result = {item.split(" ")[0]: item.split(" ")[1] for item in data_list }
print(result)

data = 'wd=搜狗&rsv_spt=1&rsv_iqid=0xd787ab5d00049167&issp=1&f=8&rsv_bp=1&rsv_idx=2&ie=utf-8&tn=baiduhome_pg&rsv_enter=1&rsv_dl=tb&rsv_sug3=7&rsv_sug1=6&rsv_sug7=101&rsv_sug2=0&rsv_btype=i&inputT=1988&rsv_sug4=2956'
res_list=data.split("&")
res_dic = {item.split('=')[0]:item.split("=")[1] for item in data.split("&")}
print(res_dic)

'''
字典转化为string
'''
params = {'wd': '搜狗', 'rsv_spt': '1', 'rsv_iqid': '0xd787ab5d00049167', 'issp': '1', 'f': '8', 'rsv_bp': '1', 'rsv_idx': '2', 'ie': 'utf-8',
       'tn': 'baiduhome_pg', 'rsv_enter': '1', 'rsv_dl': 'tb', 'rsv_sug3': '7',
       'rsv_sug1': '6', 'rsv_sug7': '101', 'rsv_sug2': '0', 'rsv_btype': 'i',
       'inputT': '1988', 'rsv_sug4': '2956'}

li = []
for key,value in params.items():
   # str=key+"="+value  #相加效率低
   str = "{}={}".format(key,value)
   li.append(str)
res = "&".join(li)
print(res)

res = "&".join(["{}={}".format(key,value) for key,value in params.items()])

#集合推导式
data = {i for i in range(10)}
print(data)

闭包：函数嵌套函数，掉用外面函数 不想立即执行内容，在该函数内嵌套函数，让内部函数工作，可以在内部封装自己想要的东西

def outer(name):
    def inner():
        msg = "{}".format(name)
        print(msg)
    return inner

v = outer("Jack")
v2 = outer("Lily")

v()
v2()

线程池：

装饰器：在不改变函数的基础上 想在函数执行前后定制功能

def outer(a1):
    def inner():
        a1()
    return inner

def x():
    print("xx")

res = outer(x)
res()

@outer
def plus(v1):
    return  v1

res = plus(1)
print(res)

def outer(func):
    def inner(*args,**kwargs):
        return func(*args,**kwargs)
    return inner

@outer
def plus(v1):
    return  v1

res = plus(1)
print(res)

"""计算一个函数的执行时间"""
import time

def coast(arg):
    def inner():
        start = time.time()
        res = arg()
        end = time.time()
        print(end - start)
        return res

    return inner
@coast
def func():
    data = 0
    for i in range(10000000000):
        data += i
    return data
func()

def repeat_func(arg):
    def inner():
        result = 0
        for i in range(5):
            res = arg()
            result += res

        return result
    return inner

@repeat_func
def f1():
    return 123

t = f1()
print(t)

def outer(args):
    def inner(a1,a2):
        return args(a1,a2)
    return inner

@outer
def plus(v1,v2):
    return  v1+v2

res = plus(1,3)
print(res)

def outer(args):
    def inner(a1):
        return args(a1)
    return inner

@outer
def plus(v1):
    return  v1

res = plus(1)
print(res)

def outer(func):
    def inner(*args,**kwargs):
        return func(*args,**kwargs)
    return inner

@outer
def plus(v1):
    return  v1

res = plus(1)
print(res)

"""
带参数的装饰器
"""
def tt(count):
    def outer(func):
        def inner(*args,**kwargs):
            r = 0
            for i in range(count):
                res = func(*args,**kwargs)
                r += res
            return r
        return inner
    return outer

@tt(5)
def f(x):
    return x

res = f(100)
print(res)

传统的装饰器是由两层嵌套，带参数的装饰器是三层。

原文地址：http://www.cnblogs.com/W505020235/p/16875270.html