Message332166
_asdict_inner attempts to manually recursively deepcopy dicts by calling type(obj) with a generator of transformed keyvalue tuples @ https://github.com/python/cpython/blob/b2f642ccd2f65d2f3bf77bbaa103dd2bc2733734/Lib/dataclasses.py#L1080 . defaultdicts are dicts so this runs but unlike other dicts their first arg has to be a callable or None:
import collections
import dataclasses as dc
@dc.dataclass()
class C:
d: dict
c = C(collections.defaultdict(lambda: 3, {}))
d = dc.asdict(c)
assert isinstance(d['d'], collections.defaultdict)
assert d['d']['a'] == 3
=>
Traceback (most recent call last):
File "boom.py", line 9, in <module>
d = dc.asdict(c)
File "/Users/spinlock/.pyenv/versions/3.7.1/lib/python3.7/dataclasses.py", line 1019, in asdict
return _asdict_inner(obj, dict_factory)
File "/Users/spinlock/.pyenv/versions/3.7.1/lib/python3.7/dataclasses.py", line 1026, in _asdict_inner
value = _asdict_inner(getattr(obj, f.name), dict_factory)
File "/Users/spinlock/.pyenv/versions/3.7.1/lib/python3.7/dataclasses.py", line 1058, in _asdict_inner
for k, v in obj.items())
TypeError: first argument must be callable or None
I understand that it isn't this bit of code's job to support every dict (and list etc.) subclass under the sun but given defaultdict is stdlib it's imo worth supporting explicitly. |
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Date |
User |
Action |
Args |
2018-12-19 22:06:45 | wrmsr | set | recipients:
+ wrmsr |
2018-12-19 22:06:44 | wrmsr | set | messageid: <1545257204.19.0.788709270274.issue35540@psf.upfronthosting.co.za> |
2018-12-19 22:06:44 | wrmsr | link | issue35540 messages |
2018-12-19 22:06:43 | wrmsr | create | |
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