Python函数修饰器之二
2019-02-28 本文已影响0人
louyang
def calc_square(numbers):
result = []
for number in numbers:
result.append(number*number)
return result
def calc_cube(numbers):
result = []
for number in numbers:
result.append(number*number*number)
return result
array = range(1,100000)
out_square = calc_square(array)
out_cube = calc_cube(array)
当我们面对上面这样的python程序，计算平方和立方各10万次。有的时候我们会希望测量这样的函数运行的时间。
我们可以这样：
import time
def calc_square(numbers):
start = time.time()
result = []
for number in numbers:
result.append(number*number)
end = time.time()
print("calc_square took " + str(end-start) + " sec")
return result
def calc_cube(numbers):
start = time.time()
result = []
for number in numbers:
result.append(number*number*number)
end = time.time()
print("calc_cube took " + str(end-start) + " sec")
return result
array = range(1,100000)
out_square = calc_square(array)
out_cube = calc_cube(array)
但是，当有更多函数需要加start/end的时候，我们就很难做了。一是代码尺寸大，修改的地方多；二是原有的代码被切割的支离破碎。
用函数修饰器可以解决这个问题，所谓修饰器就是在不改变原有函数的基础上，增加新功能。
import time
def time_it(func):
def wrapper(*args, **kwargs):
start = time.time()
result = func(*args, **kwargs)
end = time.time()
print(func.__name__ + " took " + str(end-start) + " sec")
return result
return wrapper
@time_it
def calc_square(numbers):
result = []
for number in numbers:
result.append(number*number)
return result
@time_it
def calc_cube(numbers):
result = []
for number in numbers:
result.append(number*number*number)
end = time.time()
array = range(1,100000)
out_square = calc_square(array)
out_cube = calc_cube(array)
运行结果：
$ python a.py
calc_square took 0.0116701126099 sec
calc_cube took 0.0140378475189 sec
