Failing import with py311

[gituser768]

python -c 'import springs' throws an error with python 3.11:

File ~/miniconda3/envs/term_extractor/lib/python3.11/site-packages/springs/__init__.py:5
      1 from dataclasses import dataclass
      3 from omegaconf import MISSING, SI, DictConfig, ListConfig
----> 5 from .commandline import cli
      6 from .core import (
      7     DEFAULT,
      8     cast,
   (...)
     24     validate,
     25 )
     26 from .field_utils import field

File ~/miniconda3/envs/term_extractor/lib/python3.11/site-packages/springs/commandline.py:96
     92     def __str__(self) -> str:
     93         return f"{self.short}/{self.long}"
---> 96 @dataclass
     97 class CliFlags:
     98     config: Flag = Flag(
     99         name="config",
    100         help=(
   (...)
    108         metavar="/path/to/config.yaml",
    109     )
    110     options: Flag = Flag(
    111         name="options",
    112         help="print all default options and CLI flags.",
    113         action="store_true",
    114     )

File ~/miniconda3/envs/term_extractor/lib/python3.11/dataclasses.py:1223, in dataclass(cls, init, repr, eq, order, unsafe_hash, frozen, match_args, kw_only, slots, weakref_slot)
   1220     return wrap
   1222 # We're called as @dataclass without parens.
-> 1223 return wrap(cls)

File ~/miniconda3/envs/term_extractor/lib/python3.11/dataclasses.py:1213, in dataclass.<locals>.wrap(cls)
   1212 def wrap(cls):
-> 1213     return _process_class(cls, init, repr, eq, order, unsafe_hash,
   1214                           frozen, match_args, kw_only, slots,
   1215                           weakref_slot)

File ~/miniconda3/envs/term_extractor/lib/python3.11/dataclasses.py:958, in _process_class(cls, init, repr, eq, order, unsafe_hash, frozen, match_args, kw_only, slots, weakref_slot)
    955         kw_only = True
    956     else:
    957         # Otherwise it's a field of some type.
--> 958         cls_fields.append(_get_field(cls, name, type, kw_only))
    960 for f in cls_fields:
    961     fields[f.name] = f

File ~/miniconda3/envs/term_extractor/lib/python3.11/dataclasses.py:815, in _get_field(cls, a_name, a_type, default_kw_only)
    811 # For real fields, disallow mutable defaults.  Use unhashable as a proxy
    812 # indicator for mutability.  Read the __hash__ attribute from the class,
    813 # not the instance.
    814 if f._field_type is _FIELD and f.default.__class__.__hash__ is None:
--> 815     raise ValueError(f'mutable default {type(f.default)} for field '
    816                      f'{f.name} is not allowed: use default_factory')
    818 return f

ValueError: mutable default <class 'springs.commandline.Flag'> for field config is not allowed: use default_factory

To reproduce:

conda create --name reproduce_sp_bug python=3.11 pip
conda activate reproduce_sp_bug
pip install springs
python -c 'import springs'

[soldni]

Fixed in #22! Springs is now compatible with Python 3.11.