FixedOffset serialization fails

test_fo.py

"""
Save this file as test_fo.py and run it
"""

import pprint
import json
import datetime
import pickle

jsonpickle = None
bson = None

def setup_module(module):
	module.jsonpickle = __import__('jsonpickle')
	module.bson = __import__('bson.tz_util')

def test_FixedOffsetSerializable():
	fo = bson.tz_util.FixedOffset(-60*5, 'EST')
	serialized = jsonpickle.dumps(fo)
	pprint.pprint(json.loads(serialized))
	restored = jsonpickle.loads(serialized)
	print(restored._FixedOffset__offset)
	assert vars(restored) == vars(fo)

def test_timedelta():
	td = datetime.timedelta(-1, 68400)
	serialized = jsonpickle.dumps(td)
	pprint.pprint(json.loads(serialized))
	restored = jsonpickle.loads(serialized)
	assert restored == td

def test_stdlib_pickle():
	fo = bson.tz_util.FixedOffset(-60*5, 'EST')
	serialized = pickle.dumps(fo)
	pprint.pprint(serialized)
	restored = pickle.loads(serialized)
	print(restored._FixedOffset__offset)
	assert vars(restored) == vars(fo)

class FixedOffset(datetime.tzinfo):
    def __init__(self, offset):
        self.offset = datetime.timedelta(offset)

    def __getinitargs__(self):
        return self.offset,

    def utcoffset(self, dt):
        return self.offset

    def tzname(self, dt):
        return 'name'

    def dst(self, dt):
        return datetime.timedelta(0)

def test_nested_objects():
	o = FixedOffset(99)
	serialized = jsonpickle.dumps(o)
	pprint.pprint(json.loads(serialized))
	restored = jsonpickle.loads(serialized)
	assert restored.offset == datetime.timedelta(99)

def test_datetime_with_fixed_offset():
	fo = FixedOffset(-60)
	dt = datetime.datetime.now().replace(tzinfo=fo)
	serialized = jsonpickle.dumps(dt)
	pprint.pprint(json.loads(serialized))
	restored = jsonpickle.loads(serialized)
	assert restored == dt


setup_params = dict(
	install_requires=[
		'jsonpickle',
		'pymongo',
	],
	setup_requires=[
		'pytest_runner',
	],
	tests_require=[
		'pytest',
	],
)

if __name__ == '__main__':
	import sys
	sys.argv[1:1] = ['pytest']
	__import__('setuptools').setup(**setup_params)

Ugh, nevermind, that totally doesn't work.. I'll keep digging. I was misled when I wrote some test code that made me believe that the above works, but it doesn't. doh.

TypeError: __class__ assignment: 'list' object layout differs from 'tuple'

Going to try something like this... https://mail.python.org/pipermail/python-dev/2003-January/032043.html we'll see.

# crash-python.py
class Tuple(tuple):
    __slots__ = ()

class List(list):
    __slots__ = ()

t = List()
t.__class__ = Tuple
# --- >8 --- >8 ---

$ python2.7 crash-python.py
Segmentation fault: 11

$ python3.4 crash-python.py
TypeError: __class__ assignment: 'List' object layout differs from 'Tuple'

Oh well, I'll probably try a different approach, like maybe returning an instance that behaves like a tuple, but without actually being an instance. That's unfortunate, though.