函数wrapper的作用是什么 他的参数又是干嘛的呢？
import time
def performance(unit):
def perf_decorator(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(10)
