Add prefixes before dataclass attributes dynamically

prefix_meta.py

from dataclasses import dataclass


class PrefixMeta(type):
    def __new__(cls, name, bases, attrs):
        try:
            prefix = attrs["Config"].prefix
        except (KeyError, AttributeError):
            prefix = None
        if prefix:
            for attr_name, attr_value in attrs.items():
                conditions = (
                    isinstance(attr_value, str),
                    attr_value != name,
                    not attr_name.startswith("_"),
                )
                if all(conditions):
                    attrs[attr_name] = prefix + attr_value
        return dataclass(unsafe_hash=True)(super().__new__(cls, name, bases, attrs))


class Prefix(metaclass=PrefixMeta):
    pass


class Foo(Prefix):
    bar: str = "some_settings"

    class Config:
        prefix = "dev_"


th = Foo()
str(th) == Foo(bar="dev_some_settings")