import time
def performance(f):
    def fn(*args,**kw):
        t1=time.time()
        r=f(*args,**kw)
        t2=time.time()
        print "call %s() in %fs" %(f._name_,(t2-t1))
        return r
    return fn

@performance
def factorial(n):
    return reduce(lambda x,y:x*y,range(1,n+1))
print factorial(10)

Traceback (most recent call last):
  File "E:/learn python/practice4.py", line 14, in <module>
    print factorial(10)
  File "E:/learn python/practice4.py", line 7, in fn
    print "call %s() in %fs" %(f._name_,(t2-t1))
AttributeError: 'function' object has no attribute '_name_'