neodataclass.py

from dataclasses import dataclass, fields


def neodataclass(_cls=None, *, init=True, repr=True, eq=True, order=False,
                 unsafe_hash=False, frozen=False):
    """ Provides a wrapper around dataclass that silently filters out
    any keyword arguments provided to __init__ that do not exist as
    fields for that class.
    """

    def wrap(cls):
        """ The wrapper implementation, the outline of which is copied
        from the standard library code to make functionality as
        transparent as possible."""

        # Generate the dataclass as normal
        k = dataclass(cls, init=init, repr=repr, eq=eq, order=order,
                      unsafe_hash=unsafe_hash, frozen=frozen)

        # Look for an __init__ implementation to override. If this isn't
        # found then simply carry on as normal with the original
        # dataclass.
        try:
            init_function = getattr(k, "__init__")
        except AttributeError:
            pass
        else:

            # Extract a list of all the field names for this class
            field_names = [field.name for field in fields(k)]

            def init_wrapper(*args, **kwargs):
                """ Alternative __init__ implementation that filters
                out redundant keyword arguments by checking against
                the list of known fields
                """

                # Create a filtered dictionary of keyword arguments...
                filtered_kwargs = {name: value
                                   for name, value in kwargs.items()
                                   if name in field_names}

                # ...and pass that to the original __init__ function.
                return init_function(*args, **filtered_kwargs)

            # Finally, assign the wrapped __init__ back to the
            # attribute.
            setattr(k, "__init__", init_wrapper)

        return k

    if _cls is None:
        return wrap

    return wrap(_cls)


@neodataclass
class Person:
    name: str = None
    age: int = None


def main():
    print(Person(**{"name": "Alice", "age": 33, "gender": "F"}))
    print(Person(name="Bob", age=44, gender="M"))


if __name__ == "__main__":
    main()