impl_pydantic.py

from typing import Optional
from pydantic import validator
from pydantic.dataclasses import dataclass


@dataclass(frozen=True)
class Position:
    longitude: float
    latitude: float
    address: Optional[str] = None

    @validator("longitude")
    def longitude_value_range(cls, v):
        if not (-180 <= v <= 180):
            raise ValueError(f"Longitude was {v}, but must be in [-180, +180]")
        return v

    @validator("latitude")
    def latitude_value_range(cls, v):
        if not (-90 <= v <= 90):
            raise ValueError(f"Latitude was {v}, but must be in [-90, +90]")
        return v


pos1 = Position(49.0127913, 8.4231381, "Parkstraße 17")
pos2 = Position(longitude=42.1238762, latitude=9.1649964)


def get_distance(p1: Position, p2: Position) -> float:
    pass