python 装饰器详解
装饰器
装饰器其实就是一个闭包，把一个函数当做参数然后返回一个替代版函数
装饰器有２个特性：
一是可以把被装饰的函数替换成其他函数，
二是可以在加载模块时候立即执行
def w1(func):
def inner():
# 验证1
# 验证2
# 验证3
func()
return inner
@w1
def f1():
print('f1')
装饰器(decorator)功能
1. 引⼊⽇志
2. 函数执⾏时间统计
3. 执⾏函数前预备处理
4. 执⾏函数后清理功能
5. 权限校验等场景
6. 缓存
上代码直观感受
#定义函数： 完成包裹数据
def makeBold(fn):
def wrapped():
return "<b>" + fn() + "</b>"
return wrapped
@makeBold
def test1():
return "hello world-1"
#定义函数： 完成包裹数据
def makeItalic(fn):
def wrapped():
return "<i>" + fn() + "</i>"
return wrapped
@makeItalic
def test2():
return "hello world-2"
@makeBold
@makeItalic
def test3():
return "hello world-3"
print(test1())
print(test2())
print(test3())
装饰器对无参函数进行装饰
from time import ctime, sleep
def timefun(func):
def wrappedfunc():
print("%s called at %s"%(func.__name__, ctime()))
func()
return wrappedfunc
@timefun
def foo():
print("I am foo")
foo()
sleep(2)
foo()
装饰器对有参函数进行装饰
from time import ctime, sleep
def timefun(func):
def wrappedfunc(a, b):
print("%s called at %s"%(func.__name__, ctime()))
print(a, b)
func(a, b)
return wrappedfunc
@timefun
def foo(a, b):
print(a+b)
foo(3,5)
sleep(2)
foo(2,4)
装饰器对不定长参数函数进行装饰
from time import ctime, sleep
def timefun(func):
def wrappedfunc(*args, **kwargs):
print("%s called at %s"%(func.__name__, ctime()))
func(*args, **kwargs)
return wrappedfunc
@timefun
def foo(a, b, c):
print(a+b+c)
foo(3,5，7）
sleep(2)
foo(2,4，9)
装饰器对带有返回值的函数进行装饰
from time import ctime, sleep
def timefun(func):
def wrappedfunc(*args, **kwargs):
print("%s called at %s"%(func.__name__, ctime()))
ret = func()
return ret
return wrappedfunc
@timefun
def foo():
print("I am foo")
@timefun
def getInfo():
return '----hahah---'
带有参数的装饰器
from time import ctime, sleep
def timefun_arg(pre="hello"):
def timefun(func):
def wrappedfunc():
print("%s called at %s %s"%(func.__name__, ctime(), pre))
return func()
return wrappedfunc
return timefun
@timefun_arg(“sxt")
def foo():
print("I am foo")
@timefun_arg("python")
def too():
print("I am too" )
from time import ctime, sleep def timefun(func): def wrappedfunc(*args, **kwargs): print("%s called at %s"%(func.__name__, ctime())) func(*args, **kwargs) return wrappedfunc @timefun def foo(a, b, c): print(a+b+c) foo(3,5,7) sleep(2) foo(2,4,9)
