Dataclasses has become a dependency of dacite on python 3.7.x

[mvalkon]

I'm getting a confusing error with dacite 0.0.25. I'm using dacite in anAWS Lambda function (which is why the traceback looks a little funny), and I'm getting the following exception when importing dacite.config.Config:

AttributeError: module 'typing' has no attribute '_ClassVar'
Traceback (most recent call last):
  File "/var/lang/lib/python3.7/imp.py", line 234, in load_module
    return load_source(name, filename, file)
  File "/var/lang/lib/python3.7/imp.py", line 171, in load_source
    module = _load(spec)
  File "<frozen importlib._bootstrap>", line 696, in _load
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/var/task/cris/queue_event.py", line 8, in <module>
    from dacite import Config, from_dict
  File "/var/task/dacite/__init__.py", line 1, in <module>
    from dacite.config import Config
  File "/var/task/dacite/config.py", line 14, in <module>
    @dataclass
  File "/var/task/dataclasses.py", line 958, in dataclass
    return wrap(_cls)
  File "/var/task/dataclasses.py", line 950, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen)
  File "/var/task/dataclasses.py", line 801, in _process_class
    for name, type in cls_annotations.items()]
  File "/var/task/dataclasses.py", line 801, in <listcomp>
    for name, type in cls_annotations.items()]
  File "/var/task/dataclasses.py", line 659, in _get_field
    if (_is_classvar(a_type, typing)
  File "/var/task/dataclasses.py", line 550, in _is_classvar
    return type(a_type) is typing._ClassVar

For some reason, the 0.0.25 release introduces dataclasses==0.6 as a dependency even though I'm on python 3.7.2

% pip --version
pip 19.0.3 from /usr/local/opt/pyenv/versions/3.7.2/envs/test/lib/python3.7/site-packages/pip (python 3.7)
% python --version
Python 3.7.2
% pip freeze
% pip install dacite
Collecting dacite
  Using cached https://files.pythonhosted.org/packages/48/a8/218d76025df9b63f6896f91a432a2ccbc658efb8c404e2d0af8c28f89dde/dacite-0.0.25-py3-none-any.whl
Collecting dataclasses (from dacite)
  Using cached https://files.pythonhosted.org/packages/26/2f/1095cdc2868052dd1e64520f7c0d5c8c550ad297e944e641dbf1ffbb9a5d/dataclasses-0.6-py3-none-any.whl
Installing collected packages: dataclasses, dacite
Successfully installed dacite-0.0.25 dataclasses-0.6
% pip freeze
dacite==0.0.25
dataclasses==0.6

If I attempt to install the 0.0.24, the dataclasses dependency is not present

pip install dacite==0.0.24
Collecting dacite==0.0.24
  Using cached https://files.pythonhosted.org/packages/60/a8/50cc19f7254f688c41140fd33531499f7d0b529617757c119a5b0e95ce01/dacite-0.0.24-py3-none-any.whl
Installing collected packages: dacite
Successfully installed dacite-0.0.24
% pip freeze
dacite==0.0.24

I went through the setup.py and cannot really understand where the dataclasses dependency leaks in on a 3.7 python. At the moment I've resorted to downgrading to 0.0.24 for my use case.

[konradhalas]

@mvalkon thank you for reporting this issue. I have no idea what is going on, but I will check it :)

[micah-williamson]

I'm having this same issue. It relates to conditional dependencies in the setup file.

PR here-

https://github.com/konradhalas/dacite/pull/49

[konradhalas]

Fixed, please try with newest version 0.0.26. Now I explicite "deploy" package on PyPI with Python 3.7 version.

[micah-williamson]

Thanks for the fast response. That worked!

[mvalkon]

Thanks for the fix @konradhalas

[konradhalas]

No problem guys, it was my fault. Thank you for reporting!

[beetree]

Still having the same issue with version 1.2.0

Here's log from lambda:

Function Logs:
START RequestId: d4d174f0-60ea-474c-bcad-d865736d2fc0 Version: $LATEST
[ERROR] AttributeError: module 'typing' has no attribute '_ClassVar'
Traceback (most recent call last):
  File "/var/lang/lib/python3.8/imp.py", line 234, in load_module
    return load_source(name, filename, file)
  File "/var/lang/lib/python3.8/imp.py", line 171, in load_source
    module = _load(spec)
  File "<frozen importlib._bootstrap>", line 702, in _load
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/var/task/src/new_order/order_load_from_shopify.py", line 2, in <module>
    from lib.Order import Order
  File "/var/task/lib/Order.py", line 3, in <module>
    from dacite import from_dict
  File "/var/task/aws_packages/dacite/__init__.py", line 1, in <module>
    from dacite.config import Config
  File "/var/task/aws_packages/dacite/config.py", line 6, in <module>
    class Config:
  File "/var/task/aws_packages/dataclasses.py", line 958, in dataclass
    return wrap(_cls)
  File "/var/task/aws_packages/dataclasses.py", line 950, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash, frozen)
  File "/var/task/aws_packages/dataclasses.py", line 800, in _process_class
    cls_fields = [_get_field(cls, name, type)
  File "/var/task/aws_packages/dataclasses.py", line 800, in <listcomp>
    cls_fields = [_get_field(cls, name, type)
  File "/var/task/aws_packages/dataclasses.py", line 659, in _get_field
    if (_is_classvar(a_type, typing)
  File "/var/task/aws_packages/dataclasses.py", line 550, in _is_classvar
    return type(a_type) is typing._ClassVarEND RequestId: d4d174f0-60ea-474c-bcad-d865736d2fc0
REPORT RequestId: d4d174f0-60ea-474c-bcad-d865736d2fc0  Duration: 4879.35 ms    Billed Duration: 4900 ms    Memory Size: 128 MB Max Memory Used: 30 MB  
Unknown application error occurred