装饰器（1）

https://www.cnblogs.com/yuanchenqi/articles/5830025.html

#简单装饰器

import time

def show_time(func):
    def wraper():
        start_time=time.time()
        func()
        end_time=time.time()
        print('spend %s' %(end_time-start_time))
    return wraper

@show_time
def foo():
    print("hello foo")
    time.sleep(3)

foo()

#带参数的被装饰函数

import time

def show_time(func):
    def wraper(a,b):
        start_time=time.time()
        func(a,b)
        end_time=time.time()
        print('spend %s' %(end_time-start_time))
    return wraper

@show_time
def add(a,b):
    time.sleep(1)
    print(a+b)

add(2,4)

#不定长参数

import time

def show_time(func):

    def wraper(*args,**kwargs):
        start_time=time.time()
        func(*args,**kwargs)
        end_time=time.time()
        print('spend %s' %(end_time-start_time))

    return wraper

@show_time
def add(*args,**kwargs):
    time.sleep(1)
    sum=0
    for i in args:
        sum+=1
    print(sum)

add(2,4,8,9)

# 带参数的装饰器

import time

def time_logger(flag=0):
    def show_time(func):
        def wrapper(*args, **kwargs):
            start_time = time.time()
            func(*args, **kwargs)
            end_time = time.time()
            print('spend %s' % (end_time - start_time))
            if flag:
                print('将这个操作的时间记录到日志中')
        return wrapper
    return show_time

@time_logger(3)
def add(*args, **kwargs):
    time.sleep(1)
    sum = 0
    for i in args:
        sum += i
    print(sum)

add(2, 7, 5)

#多层装饰器

def makebold(fn):
    def wrapper():
        return "<b>" + fn() + "</b>"
    return wrapper

def makeitalic(fn):
    def wrapper():
        return "<i>" + fn() + "</i>"
    return wrapper

@makebold
@makeitalic
def hello():
    return "hello alvin"

hello()

#类装饰器

import time

class Foo(object):
    def __init__(self,func):
        self._func=func

    def __call__(self):
        start_time=time.time()
        self._func()
        end_time=time.time()
        print('spend %s'%(end_time-start_time))

@Foo
def bar():
    print('bar')
    time.sleep(2)

bar()