copy.deepcopy() with datetime objects fails with "TypeError: __init__() takes exactly 2 arguments (1 given)"

[ralt]

Apparently since this commit: 96d65f3

[ralt]

Sorry, I did this ticket a bit too hastily. Here is a reproducer:

import copy
import datetime
import yaml

copy.deepcopy(yaml.constructor.timezone(datetime.timedelta(seconds=0)))

[ralt@tag ~]$ python2 /tmp/r.py
Traceback (most recent call last):
  File "/tmp/r.py", line 6, in <module>
    copy.deepcopy(yaml.constructor.timezone(datetime.timedelta(seconds=0)))
  File "/usr/lib64/python2.7/copy.py", line 190, in deepcopy
    y = _reconstruct(x, rv, 1, memo)
  File "/usr/lib64/python2.7/copy.py", line 329, in _reconstruct
    y = callable(*args)
TypeError: __init__() takes exactly 2 arguments (1 given)

It is when dealing with datetime objects.

[cognifloyd]

This only applies to python2. In python3, it uses the stdlib timezone objects.

So the minimal timezone object (yaml.constructor.timezone) needs __copy__ and __deepcopy__ methods.

[cognifloyd]

Just to add a slightly more verbose description of this issue:
This bug occurs in python 2 + pyyaml 5.3+ when:

1. parse a document with a yaml timestamp
2. pyyaml converts that timestamp to a timezone aware datetime object where tzinfo is an instance of yaml.constructor.timezone
3. use copy.deepcopy to copy the python object (typically a dict) that resulted from parsing the yaml
4. copy.deepcopy fails miserably with the TypeError as described above because it can't copy yaml.constructor.timezone.

[ralt]

Thank you, you are much better at summarizing usefully the state of things :)

As of right now, we have reverted pyyaml to older than 5.3. Should we implement those methods or do you plan on fixing it in pyyaml?

[cognifloyd]

This broke one of my transient dependencies, and pyyaml is a transient dep of yet another transient dep... I don't have resources to fix it right now so I also pyyaml to <5.3 on py2.7.

But pyyaml is the proper place to fix this instead of pinning transient deps.

[ingydotnet]

If someone wants to submit a PR (extra credit if it has tests) I can get this out soon.

[ralt]

@ingydotnet there you go (not from me)

[ingydotnet]

thanks