Example of dataclass with property

data.py

from dataclasses import dataclass
from typing import List, Tuple

@dataclass(frozen=True)
class Position:
    name: str
    dates: List[int]
    items: Tuple
    lon: float = 0.0
    lat: float = 0.0
    
    @property
    def sorted_items(self):
        if self.items:
            return tuple(sorted(list(self.items)))
        return ()


p = Position(name="NullIsle", items=('d','c'), dates=[0,1,2], lon=1.1, lat=2.2)
print(p, p.lon)

try:
    p.lat = 1.0  # simple type cannot be changed
    print(p, p.lat)
except Exception as err:
    print(err)
    
p.dates[0] = 10  # list values are NOT immutable in frozen dataclass
print(p, p.dates)

p.dates.append(20)  # list is NOT immutable in frozen dataclass
print(p, p.dates)

p.dates.append('x')  # list "type" not enforced in frozen dataclass
print(p, p.dates)

# p.items = ('c', 'd')  # tuple is an immutable type in Python

print(p.sorted_items)


q = Position(name="NullIsle", items=['d','c'], dates=[0,1,2], lon=1.1, lat=2.2)
print(q.items)  # type not enforced
print(q.sorted_items)