python decorator snappet 1

1.什么是decorator?

装饰器就是，装饰你目标的东西。其实wapper来理解更好~就好比钢铁侠的盔甲！

def decorator(fun):
    def warrper(name):
        start = time.time()
        fun(name)
        runtime = time.time() - start

        print runtime
    return warrper

@decorator
def do_something(name):
    for i in range(10000000):
        pass
    print 'name:',name

if __name__ == '__main__':
    do_something('Li yun long')

name: Li yun long
0.27599978447

让参数不固定：

def decorator(fun):
    def wapper(*args,**kwargs):
        start = time.time()
        fun(*args,**kwargs)
        runtime = time.time() - start
        print runtime
    return wapper

@decorator
def do_something(user,name):
    for i in range(10000000):
        pass
    print "user:",user
    print "name:",name

if __name__ == '__main__':
    do_something('Li yun long','yun long')

user: Li yun long
name: yun long
0.30999994278

改装一下，让它带参数，
···
def decorator(num):
def _decorator(fun):
def wapper(args,kwargs):
start = time.time()
for i in xrange(num):
fun(args,**kwargs)
runtime = time.time() - start
print runtime
return wapper
return _decorator

@decorator(2)
def do_something(user,name):
for i in range(10000000):
pass
print "user:",user
print "name:",name

if name == 'main':
do_something('Li yun long','yun long')
···

user: Li yun long
name: yun long
user: Li yun long
name: yun long
0.5

尬图1.png

不要试图在里面些两个，第二个不会运行的.

尬图2.png

那么,调用顺序呢？

def decorator(fun):
    print "decorator"
    def warrper():
        print "wapper"
        start = time.time()
        fun()
        runtime = time.time() - start
        print runtime
    return warrper

@decorator
def do_something():
    for i in range(10000000):
        pass
    print 'do_something'

它的结果是：

尬图3.png

被装饰器装饰过的函数名：

def decorator(fun):
   #print "decorator"
   def warrper(name):
       #print "wapper"
       start = time.time()
       fun(name)
       runtime = time.time() - start
       print runtime
   return warrper


@decorator
def do_something(name):
   for i in range(10000000):
       pass
   print 'do_something',name

if __name__ == '__main__':
   print do_something.__name__

尬图4.png

用functools:

import functools
def decorator(fun):
   @functools.wraps(fun)
   def warrper(name):
       start = time.time()
       fun(name)
       runtime = time.time() - start
       print runtime
   return warrper

@decorator
def do_something(name):
   for i in range(10000000):
       pass
   print 'do_something',name

if __name__ == '__main__':
   print do_something.__name__

尬图5.png