How does one ignore extra arguments passed to a data class?

Question

I\'d like to create a config dataclass in order to simplify whitelisting of and access to specific environment variables (typing os.environ[\

Answer 1

I would just provide an explicit __init__ instead of using the autogenerated one. The body of the loop only sets recognized value, ignoring unexpected ones.

Note that this won't complain about missing values without defaults until later, though.

@dataclass
class Config(init=False):
    VAR_NAME_1: str
    VAR_NAME_2: str

    def __init__(self, **kwargs):
        names = set([f.name for f in dataclasses.fields(self)])
        for k, v in kwargs.items():
            if k in names:
                setattr(self, k, v)

Alternatively, you can pass a filtered environment to the default Config.__init__.

field_names = set(f.name for f in dataclasses.fields(Config))
c = Config(**{k:v for k,v in os.environ.items() if k in field_names})