New submission from Erez Zinman <erezinman.program...@gmail.com>:
This bug occurs when copying/pickling an ordered-dict subtype that has default
items. The initialization function that's returned is **not** `object.__new__`
so the default items are set when the copied/pickled item is created. The
problem I encountered is that when deleting an initial item, it appears in the
copy. See the MWE below:
```
from collections import OrderedDict
import copy
class A(OrderedDict):
def __init__(self):
self['123'] = 123
a = A()
del a['123']
copy.copy(a)
# --> A([('123', 123)])
```
This can cause other problems as well, because you don't assume that the class
is re-initialized on deserialization/copy.
----------
components: Library (Lib)
messages: 376627
nosy: erezinman
priority: normal
severity: normal
status: open
title: Error copying an instance of a subclass of OrderedDict
type: behavior
versions: Python 3.6
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Python tracker <rep...@bugs.python.org>
<https://bugs.python.org/issue41751>
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