装饰器

装饰器

把一个函数当作参数传递给另一个函数 返回一个替代版的函数
本质上就是一个返回函数的函数

在不改变原函数的基础上 给函数增加功能

def add_one(number):
     return number + 1
a = add_one(2)
print(a)

函数可以作为参数被传递

# def say_hello(name):
#     return f"Hello {name}"
# def be_some(name):
#     return f"Your {name}"
#
# def greet_bob(func):
#     return func("Bob")
#
# print(greet_bob(say_hello))
# print(greet_bob(be_some))

# def say():
#     # print('*********')
#     print('hello')
# def hello():
#     print('!!!!!!!!!!!!!!hello')

def fun(f):
    def inner():
        print('*********')
        f()
        print('############')
    return inner
@fun #语法糖
def hello():
    print('!!!!!!!!!!!!!!hello')
# say()
# say = fun(say)
# print(say)
# say()
# hello = fun(hello)
# hello()

def outer(f):
    def inner(age):
        if age <=0:
            age = 0
        f(age)
    return inner
@outer
def say(age):
    print('year old:',age)
say(-1)
say(-10)

装饰器实现一个函数计时器

1.被装饰的函数有返回值怎么办
2.如何保留被装饰函数的函数名和帮助信息文档

import time
import random
import string
import functools
li = [random.choice(string.ascii_letters) for i in range(100)]

def timeit(func):
    @functools.wraps(func)
    def wrapper(*args, **kwargs):  # 接收可变参数 和关键字参数
        """这是一个装饰器timeit"""
        # 在函数运行只前
        start_time = time.time()
        # 执行函数
        res = func(*args, **kwargs)
        # 在函数运行之后
        end_time = time.time()
        print('运行时间为:%.6f' % (end_time - start_time))
        return res
    return wrapper
@timeit
def con_add():
    s = ''
    for i in li:
        s += (i + ',')
    print(s)
@timeit
def join_add():
    print(','.join(li))
# con_add()
# join_add()

带参数的装饰器

import time
import functools
def log(kind):
    def add_log(func):
        @functools.wraps(func)
        def wrapper(*args,**kwargs):
            start_time = time.time()
            res = func(*args,**kwargs)
            end_time = time.time()
            print('<%s> [%s] 函数名:%s,运行时间:%.6f,运行返回值的结果'
              ':%d' %(kind,time.ctime(),func.__name__,
                      end_time-start_time,res))
            return res
        return wrapper
    return add_log
@log('debug')
def add(x,y):
    time.sleep(1)
    return x+y
add(1,10)

练习

import time
import functools
def add_log(func):
    @functools.wraps(func)
    def wrapper(*args,**kwargs):
        start_time = time.time()
        res = func(*args,**kwargs)
        end_time = time.time()
        print('[%s] 函数名:%s,运行时间:%.6f,运行返回值的结果'
              ':%d' %(time.ctime(),func.__name__,
                      end_time-start_time,res))
        return res
    return wrapper
@add_log
def add(x,y):
    time.sleep(1)
    return x+y

add(1,10)

import functools
import inspect
login_session = ['root','admin','redhat']
def is_login(fun):
    @functools.wraps(fun)
    def warapper(*args,**kwargs):#('root',)
        if args[0] in login_session:
            temp = fun(*args,**kwargs)
            return temp
        else:
            print('Error:%s 没有登陆成功' %(args[0]))
    return warapper
def is_admin(fun):
    @functools.wraps(fun)
    # """
    #  inspect.getcallargs会返回一个字典
    #  key:形参
    #  value:对应的实参
    # """
    def wrapper(*args,**kwargs):
        inspect_res = inspect.getcallargs(fun,*args,**kwargs)
        print('inspect的返回值是:%s' %(inspect_res))
        if inspect_res.get('name') == 'root':
            temp = fun(*args,**kwargs)
            return temp
        else:
            print('not root user,no permisson add user')
    return wrapper
@is_login
@is_admin
def add_user(name): # is_login((is_admin(adduser)) is_login(wrapper())
    print('add_user')
add_user('python')

import functools
def required_ints(func):
    @functools.wraps(func)
    def wrapper(*args,**kwargs): # (1,2,....)
        for i in args:
            # if isinstance(i,int):
            #     pass
            # else:
            #     print('函数所有的参数并非全是int型')
            if not  isinstance(i,int):
                print('函数所有的参数并非都是int型')
                break
        else:
            res = func(*args,**kwargs)
            return res
    return wrapper
@required_ints
def add(a,b):
    return a+b
@required_ints
def mymax(a,b,c,d):
    return max(a,b,c,d)
print(add(1,2.0))

import functools
def required_type(*kind):
    def require(fun):
        @functools.wraps(fun)
        def wrapper(*args,**kwargs):
            for i in args:
                if not isinstance(i,kind):
                    print('函数所有的参数并非',kind)
                    break
            else:
                res = fun(*args,**kwargs)
                return res
        return wrapper
    return require
# a = 1.0
# print(isinstance(a,(int,float)))
@required_type(int,float)
def add(a,b):
    return a+b
print(add(1,1.2))

来源：CSDN

作者：Aa. NiceMan

链接：https://blog.csdn.net/AaNiceMan/article/details/103822720