squashed_class.py

from dataclasses import dataclass, fields, asdict
from json import dumps


@dataclass
class Foo:
    a: int
    b: str


@dataclass
class Bar:
    c: float
    d: list


@dataclass
class Bin(Foo, Bar):
    def __init__(self, foo_data: Foo, bar_data: Bar):
        """
        If given, the first argument of `super` specifies where in the class's method resolution
        order a search for methods and attributes should start. The search will start *after* the
        type given.
        
        Here, the method resolution order is:
          Bin -> Foo -> Bar -> object
        
        Thus:
          - To call `Foo.__init__`, we pass `Bin` as the first argument, because `Bin` is right
            before `Foo` in the method resolution order.
          - To call `Bar.__init__`, we pass `Foo` as the first argument, because `Foo` is right
            before `Bar` in the method resolution order.
        
        Of course, you could also just call `Foo.__init__` and `Bar.__init__` directly too.
        """
        super(Bin, self).__init__(**{field.name: getattr(foo_data, field.name) for field in fields(instance)})
        super(Foo, self).__init__(**{field.name: getattr(bar_data, field.name) for field in fields(instance)})

    baz: list # Required so that `baz` is included in `asdict`, `repr`, etc.

    @property
    def baz(self):
        return [self.a, self.b, self.c, self.d]

if __name__ == "__main__":
    foo = Foo(1, "two")
    bar = Bar(3.0, ["four"])
    bin = Bin(foo, bar)
    print("Representation of bin:", repr(bin))
    print("Dict of bin:", dumps(asdict(bin), indent=4))