Ok...python standard modules includes code that define list. By writing list = [] you are breaking that code. That’s why it’s a keyword and should not be used. ... list is a built-in type. It you name anything list it will mask the original for the used namespace. More on stackoverflow.com

I do really like this pep and I think it has grounds for making python a lot better for typing. The only thing i dislike is the type keyword. Doesn’t feel pythonic More on reddit.com

None is a builtins instance. It is returned in a function when nothing is returned. For example this function: def fun(): x = 2 y = 3 Is equivalent to: def fun(): x = 2 y = 3 return Which is equivalent to: def fun(): x = 2 y = 3 return None The last way is more explicit. The print function is not equivalent to the return statement. It will always print a value. def fun(): x = 2 y = 3 print('Hello') return None When called: output = fun() Hello will display but output will have the value None. If instead: def fun(): x = 2 y = 3 return 'Hello' When the function is called: fun() You will see the value returned 'Hello'. When called and assigned to a variable: output = fun() you will not see any value displayed because it is stored in the variable output which has the value 'Hello'. More on reddit.com

After some digging around, additional research and testing I have then found out that its a limitation of dataclasses since at least what I understood it writes its own __init__ and doesn't call super() which made the limitation ( But could be wrong ). I have chosen to use metaclasses instead and then create the Singleton that way like because that worked as indented where in my situation if the costum_config is set as first instantiation then its remembered and if not then its falling back to the settings file I have as default And I did also test creating i instance using default and then try creating a extra instance with a costums settings file and it still returned the first instance as expectedAnd in tests where I created with default first and then created a second with a costum then it still returned the default since that were created first also as expected So in essence the issue were that I were using a class type there were intended for the scope of what I were trying from configparser import ConfigParser from os import path class Singleton(type): _instance = {} def __call__(cls, *args, **kwargs): if cls not in cls._instance: cls._instance[cls] = super(Singleton, cls).__call__(*args, **kwargs) return cls._instance[cls] class Settings(metaclass=Singleton): costum_config_path: str = "" _DEFAULT_CONFIG_PATH: str = "settings.cfg" _config_file: str = "" __config_obj: ConfigParser def __init__(self, costum_config: str = None): self.__config_obj = ConfigParser() if costum_config: self._config_file = costum_config else: self._config_file = self._DEFAULT_CONFIG_PATH if not path.isfile(self._config_file): self.__config_obj = self.__generate_default(self.__config_obj) with open(self._config_file, "w", encoding="utf8") as file_handler: self.__config_obj.write(file_handler) print(f"Wrote the settings to {self._config_file}") self.__config_obj.read(self._config_file) More on reddit.com