django views.py 中， datetime.datetime.now() 作为默认参数时值不会改变

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This topic created in 3384 days ago, the information mentioned may be changed or developed.

hi ，如题，不知道这是不是 django 的特性？直接用 python 试了没这效果。

import datetime
def test(a, b=datetime.datetime.now()):
    print a
    print "b %s" %b
    print "c %s" %datetime.datetime.now()

test(2)

输出结果 b 的值不会改变， c 的正常。

django

Code

14 replies • 2017-02-07 20:26:10 +08:00

111111111111

Feb 6, 2017

In [1]: import datetime

In [2]: def test(a, b=datetime.datetime.now()):
...: print a
...: print "b %s" %b
...: print "c %s" %datetime.datetime.now()
...:

In [3]: import time

In [4]: for i in range(6):
...: time.sleep( 2)
...: test(i)
...:
0
b 2017-02-06 11:53:42.707000
c 2017-02-06 11:55:00.035000
1
b 2017-02-06 11:53:42.707000
c 2017-02-06 11:55:02.039000
2
b 2017-02-06 11:53:42.707000
c 2017-02-06 11:55:04.044000
3
b 2017-02-06 11:53:42.707000
c 2017-02-06 11:55:06.049000

111111111111

Feb 6, 2017

http://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000/001374738449338c8a122a7f2e047899fc162f4a7205ea3000

111111111111

Feb 6, 2017

@111111111111 打开之后搜索“原因解释如下：”