python decorator修改的函数的返回值是否只能为非类型
我编写了一个decorator来获取程序的运行时,但是函数返回值变为Nonetypepython decorator修改的函数的返回值是否只能为非类型,python,decorator,nonetype,Python,Decorator,Nonetype,我编写了一个decorator来获取程序的运行时,但是函数返回值变为Nonetype def gettime(func): def wrapper(*args, **kw): t1 = time.time() func(*args, **kw) t2 = time.time() t = (t2-t1)*1000 print("%s run time is: %.5f ms"%(func.__name__, t
def gettime(func):
def wrapper(*args, **kw):
t1 = time.time()
func(*args, **kw)
t2 = time.time()
t = (t2-t1)*1000
print("%s run time is: %.5f ms"%(func.__name__, t))
return wrapper
如果不使用decorator,则返回值是正确的
A = np.random.randint(0,100,size=(100, 100))
B = np.random.randint(0,100,size=(100, 100))
def contrast(a, b):
res = np.sum(np.equal(a, b))/(A.size)
return res
res = contrast(A, B)
print("The correct rate is: %f"%res)
结果是:正确率是:0.012400
如果我使用装饰器:
@gettime
def contrast(a, b):
res = np.sum(np.equal(a, b))/len(a)
return res
res = contrast(A, B)
print("The correct rate is: %f"%res)
将报告一个错误:
contrast run time is: 0.00000 ms
TypeError:必须是实数,而不是NoneType
当然,如果我删除print
语句,我可以获得正确的运行时间,但是res
接受非类型。由于包装器替换了修饰过的函数,它还需要传递返回值:
def gettime(func):
def wrapper(*args, **kw):
t1 = time.time()
func(*args, **kw)
t2 = time.time()
t = (t2-t1)*1000
print("%s run time is: %.5f ms"%(func.__name__, t))
return wrapper
def wrapper(*args, **kw):
t1 = time.time()
ret = func(*args, **kw) # save it here
t2 = time.time()
t = (t2-t1)*1000
print("%s run time is: %.5f ms"%(func.__name__, t))
return ret # return it here
或者你可以:
def gettime(func):
def wrapper(*args, **kw):
t1 = time.time()
func(*args, **kw)
t2 = time.time()
t = (t2-t1)*1000
print("%s run time is: %.5f ms"%(func.__name__, t))
print("The correct rate is: %f"%func(*args,**kw))
return wrapper
@gettime
def contrast(a, b):
res = np.sum(np.equal(a, b))/a.size
return res
contrast(A,B)