corrscope/ovgenpy/config.py

107 wiersze
3.1 KiB
Python

from io import StringIO
from typing import ClassVar
from ovgenpy.utils.keyword_dataclasses import dataclass, fields
from ruamel.yaml import yaml_object, YAML
class MyYAML(YAML):
def dump(self, data, stream=None, **kw):
inefficient = False
if stream is None:
inefficient = True
stream = StringIO()
YAML.dump(self, data, stream, **kw)
if inefficient:
return stream.getvalue()
# https://yaml.readthedocs.io/en/latest/dumpcls.html
# >Only yaml = YAML(typ='unsafe') loads and dumps Python objects out-of-the-box. And
# >since it loads any Python object, this can be unsafe.
# I assume roundtrip is safe.
yaml = MyYAML()
def register_config(cls=None, *, always_dump: str = ''):
""" Marks class as @dataclass, and enables YAML dumping (excludes default fields).
dataclasses.dataclass is compatible with yaml.register_class.
typing.NamedTuple is incompatible.
"""
def decorator(cls: type):
cls.__getstate__ = _ConfigMixin.__getstate__
cls.__setstate__ = _ConfigMixin.__setstate__
cls.always_dump = always_dump
# https://stackoverflow.com/a/51497219/2683842
# YAML().register_class(cls) works... on versions more recent than 2018-07-12.
return yaml_object(yaml)(
dataclass(cls)
)
if cls is not None:
return decorator(cls)
else:
return decorator
# __init__-less non-dataclasses are also compatible with yaml.register_class.
@dataclass()
class _ConfigMixin:
"""
Class is unused. __getstate__ and __setstate__ are assigned into other classes.
Ideally I'd use inheritance, but @yaml_object and @dataclass rely on decorators,
and I want @register_config to Just Work and not need inheritance.
"""
always_dump: ClassVar[str]
# SafeRepresenter.represent_yaml_object() uses __getstate__ to dump objects.
def __getstate__(self):
""" Returns all fields with non-default value, or appeear in
self.always_dump. """
always_dump = set(self.always_dump.split())
dump_all = ('*' in always_dump)
state = {}
cls = type(self)
for field in fields(self):
name = field.name
value = getattr(self, name)
if dump_all or name in always_dump:
state[name] = value
continue
default = getattr(cls, name, object())
if value != default:
state[name] = value
return state
# SafeConstructor.construct_yaml_object() uses __setstate__ to load objects.
def __setstate__(self, state):
""" Checks that all fields match their correct types. """
self.__dict__.update(state)
for field in fields(self):
key = field.name
value = getattr(self, key)
typ = field.type
if not isinstance(value, typ):
name = type(self).__name__
raise OvgenError(f'{name}.{key} was supplied {repr(value)}, should be of type {typ.__name__}')
if hasattr(self, '__post_init__'):
self.__post_init__()
class OvgenError(Exception):
pass