JezK
Edit File: _config.py
import configparser import dataclasses from dataclasses import dataclass from pathlib import Path from typing import Callable from typing import ClassVar from typing import Optional from typing import Union from .helpers import make_path class ConfigError(BaseException): pass class MissingConfig(ConfigError): pass class MissingConfigSection(ConfigError): pass class MissingConfigItem(ConfigError): pass class ConfigValueTypeError(ConfigError): pass class _GetterDispatch: def __init__(self, initialdata, default_getter: Callable): self.default_getter = default_getter self.data = initialdata def get_fn_for_type(self, type_): return self.data.get(type_, self.default_getter) def get_typed_value(self, type_, name): get_fn = self.get_fn_for_type(type_) return get_fn(name) def _parse_cfg_file(filespec: Union[Path, str]): cfg = configparser.ConfigParser() try: filepath = make_path(filespec, check_exists=True) except FileNotFoundError as e: raise MissingConfig(f"No config file found at {filespec}") from e else: with open(filepath, encoding="utf-8") as f: cfg.read_file(f) return cfg def _build_getter(cfg_obj, cfg_section, method, converter=None): def caller(option, **kwargs): try: rv = getattr(cfg_obj, method)(cfg_section, option, **kwargs) except configparser.NoSectionError as nse: raise MissingConfigSection( f"No config section named {cfg_section}" ) from nse except configparser.NoOptionError as noe: raise MissingConfigItem(f"No config item for {option}") from noe except ValueError as ve: # ConfigParser.getboolean, .getint, .getfloat raise ValueError # on bad types raise ConfigValueTypeError( f"Wrong value type for {option}" ) from ve else: if converter: try: rv = converter(rv) except Exception as e: raise ConfigValueTypeError( f"Wrong value type for {option}" ) from e return rv return caller def _build_getter_dispatch(cfg_obj, cfg_section, converters=None): converters = converters or {} default_getter = _build_getter(cfg_obj, cfg_section, "get") # support ConfigParser builtins getters = { int: _build_getter(cfg_obj, cfg_section, "getint"), bool: _build_getter(cfg_obj, cfg_section, "getboolean"), float: _build_getter(cfg_obj, cfg_section, "getfloat"), str: default_getter, } # use ConfigParser.get and convert value getters.update( { type_: _build_getter( cfg_obj, cfg_section, "get", converter=converter_fn ) for type_, converter_fn in converters.items() } ) return _GetterDispatch(getters, default_getter) @dataclass class ReadsCfg: section_header: ClassVar[str] converters: ClassVar[Optional[dict]] = None @classmethod def from_cfg_file(cls, filespec: Union[Path, str]): cfg = _parse_cfg_file(filespec) dispatch = _build_getter_dispatch( cfg, cls.section_header, converters=cls.converters ) kwargs = { field.name: dispatch.get_typed_value(field.type, field.name) for field in dataclasses.fields(cls) } return cls(**kwargs)