@functools.wraps(f)放置位置问题

import time, functools

def performance(unit):

def perf_decorator(f):

@functools.wraps(f)

def wrapper(*args,**kw):

t1 = time.time()

r = f(*args,**kw)

t2 = time.time()

t = (t2-t1)*1000 if unit == 'ms' else (t2-t1)

print 'call %s() in %f%s'%(f.__name__,t,unit)

return r

return wrapper

return perf_decorator

@performance('ms')

def factorial(n):

return reduce(lambda x,y: x*y, range(1, n+1))

print factorial.__name__

1、为什么@functools.wraps(f)不是放在 def perf_decorator(f):之前么？？

2、经过带参数的decorator（即performance('ms')）之后factorial(n)函数的函数不是应该变成了perf_decorator么？？

慕粉0220183176

2017-03-26

源自：python进阶 2-14

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2 回答

饭哥
2017-07-13

import time, functools

def performance(unit):
    def perf_ferformance(f):

        def warpper(*args,**kw):
            t1=time.time()
            r=f(*args,**kw)
            t2=time.time()
            t=(t2-t1)*1000 if unit=='ms' else (t2-t1)
            return r
        return warpper
    return perf_ferformance

@performance('ms')
def factorial(n):
    return reduce(lambda x,y: x*y, range(1, n+1))

print factorial.__name__

但是运行这段不添加@functools.wraps(f)的代码时，结果还是warpper