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typing.NamedTuple instances are not picklable Two #72437
Description
| BPO | 28250 |
|---|---|
| Nosy | @mdickinson, @ilevkivskyi |
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields:
assignee = None
closed_at = <Date 2016-09-24.07:43:35.706>
created_at = <Date 2016-09-22.19:45:06.272>
labels = ['invalid', 'library']
title = 'typing.NamedTuple instances are not picklable Two'
updated_at = <Date 2016-09-24.17:07:45.226>
user = 'https://bugs.python.org/Kurt'bugs.python.org fields:
activity = <Date 2016-09-24.17:07:45.226>
actor = 'Kurt'
assignee = 'none'
closed = True
closed_date = <Date 2016-09-24.07:43:35.706>
closer = 'mark.dickinson'
components = ['Library (Lib)']
creation = <Date 2016-09-22.19:45:06.272>
creator = 'Kurt'
dependencies = []
files = []
hgrepos = []
issue_num = 28250
keywords = []
message_count = 3.0
messages = ['277236', '277311', '277321']
nosy_count = 3.0
nosy_names = ['mark.dickinson', 'levkivskyi', 'Kurt']
pr_nums = []
priority = 'normal'
resolution = 'not a bug'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue28250'
versions = ['Python 3.5']
Activity
Kurt commentedon Sep 22, 2016
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 bpo-25665.
mdickinson commentedon Sep 24, 2016
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:
produces:
Traceback (most recent call last): File "test.py", line 11, in <module> pickle.dumps(a) AttributeError: Can't pickle local object 'my_func.<locals>.A'Kurt commentedon Sep 24, 2016
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
To: [email protected]
Sent: Saturday, September 24, 2016 1:43 AM
Subject: [bpo-28250] 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:
nosy: +mark.dickinson
resolution: -> not a bug
status: open -> closed
Python tracker <[email protected]>
<http://bugs.python.org/issue28250\>