PoC for Python configuration loading, from dict to typed object. For reference only

main.py

#! /usr/bin/env python3

import sys
from inspect import signature
from typeguard import check_type

import jinja2

import typing

g_config_loader_types = {}


class ConfigLoaderFunc:
    def __init__(self, func):
        self.func = func

    def __call__(self, *args, **kwargs):
        (s,) = args
        name = self.func.__name__
        return s._data[name] if s._data and name in s._data else None


def config_loader(*args, **kwargs):
    def inner(func):
        func.__config_loader_args__ = args
        func.__config_loader_kwargs__ = kwargs
        return ConfigLoaderFunc(func)
    return inner


def get_dict_attr(obj, attr):
    for obj in [obj] + obj.__class__.mro():
        if attr in obj.__dict__:
            return obj.__dict__[attr]
    raise AttributeError


class ConfigBase:
    def __init__(self):
        self._data = None

    def load(self, data: dict):
        data_ = {}
        for d in filter(lambda a: not a.startswith('_'), dir(self)):
            func_prop = get_dict_attr(self, d)
            if isinstance(func_prop, property):
                func_loader = func_prop.fget
                if isinstance(func_loader, ConfigLoaderFunc):
                    args = func_loader.func.__config_loader_args__
                    kwargs = func_loader.func.__config_loader_kwargs__
                    type_ = signature(func_loader.func).return_annotation
                    try:
                        check_type("", data[d], type_, None)
                        data_[d] = data[d]
                    except TypeError as e:
                        pass

                    pass
        self._data = data_


class MyConfig(ConfigBase):
    @property
    @config_loader(default="my_value")
    def test(self) -> typing.Optional[str]:
        raise ValueError


def main(argv):
    config_data = {
        'test': 'my value'
    }
    config = MyConfig()
    config.load(config_data)
    print(config.test)
    return 0


if __name__ == '__main__':
    sys.exit(main(sys.argv))