Issue 28250: typing.NamedTuple instances are not picklable Two (original) (raw)

Issue28250

Created on 2016-09-22 19:45 by Kurt, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (3)
msg277236 - (view)	Author: Kurt Dally (Kurt)	Date: 2016-09-22 19:45
Creating a namedtuple and an instance of the namedtuple in a function then returning the instance to the global namespace made the instance unpickleable, as in Issue25665.
msg277311 - (view)	Author: Mark Dickinson (mark.dickinson) *	Date: 2016-09-24 07:43
I don't think this has anything to do with namedtuple; it's true whenever you create a class in an inner scope (rather than at module level). This is by design, and these restrictions are documented: https://docs.python.org/3.6/library/pickle.html#what-can-be-pickled-and-unpickled For example, running this script: import pickle def my_func(): class A: pass a = A() return a a = my_func() pickle.dumps(a) produces: Traceback (most recent call last): File "test.py", line 11, in pickle.dumps(a) AttributeError: Can't pickle local object 'my_func..A'
msg277321 - (view)	Author: Kurt Dally (Kurt)	Date: 2016-09-24 17:07
My bad, I searched and found the issue, it very closely fit mine and the pickle module is new to me.  I hadn't yet got through  the details of  pickling.  Thanks for catching that. Kurt From: Mark Dickinson <report@bugs.python.org> To: thedomesticdog@yahoo.com Sent: Saturday, September 24, 2016 1:43 AM Subject: [] typing.NamedTuple instances are not picklable Two Mark Dickinson added the comment: I don't think this has anything to do with namedtuple; it's true whenever you create a class in an inner scope (rather than at module level). This is by design, and these restrictions are documented: https://docs.python.org/3.6/library/pickle.html#what-can-be-pickled-and-unpickled For example, running this script:     import pickle     def my_func():         class A:             pass         a = A()         return a     a = my_func()     pickle.dumps(a) produces:     Traceback (most recent call last):       File "test.py", line 11, in         pickle.dumps(a)     AttributeError: Can't pickle local object 'my_func..A' ---------- nosy: +mark.dickinson resolution:  -> not a bug status: open -> closed _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue28250> _______________________________________