dataclass_property

Add the ability to use properties with dataclasses. This allows for better input validation on dataclasses.

Most of the code base is a direct copy from dataclasses with modifications. Unfortunately, dataclasses were not written in a way where you can extend the functionality easily. I changed the code to use a class based system, so the functionality could be extended. It's still not fun to work with the dataclasses library.

Examples

from typing import Union
from dataclass_property import dataclass

@dataclass
class TimeDelta:
    hours: int = 0
    minutes: int = 0
    milliseconds: int = 0

    @property
    def seconds(self) -> int:  # default_factory is set to `int()` from the annotation
        return self._seconds

    @seconds.setter
    def seconds(self, value: Union[int, float]):
        if isinstance(value, float):
            mill = int((value % 1) * 1000)
            if mill:
                self.milliseconds = mill
        self._seconds = int(value)

td = TimeDelta(minutes=1)
td.seconds = 0.5
assert td.seconds == 0
assert td.milliseconds == 500

td = TimeDelta(seconds=0.1)
assert td.seconds == 0
assert td.milliseconds == 100

field_property example with custom defaults

from dataclass_property import dataclass, field_property

@dataclass
class Point:
    # X
    @field_property(default=1)
    def x(self) -> int:
        return self._x

    @x.setter
    def x(self, value: int):
        self._x = value

    # Y
    y: int = field_property(default=1)

    @y.getter
    def y(self) -> int:
        return self._y

    @y.setter
    def y(self, value: int):
        self._y = value

    # Z
    @field_property
    def z(self) -> int:
        return self._z

    z.default(5)

    @z.default_factory
    @classmethod
    def z(cls):
        return 5

    @z.setter
    def z(self, value: int):
        self._z = value

p = Point()
assert p.x == 1
assert p.y == 1
assert p.z == 5

p = Point(x=2, y=2, z=6)
assert p.x == 2
assert p.y == 2
assert p.z == 6