dataclasses, InitVar and properties

dataclasses_init_var_properties.py

from dataclasses import dataclass, field, InitVar


@dataclass
class A:
    _x: int = field(init=False)
    x: InitVar[int]

    def __post_init__(self, x: int) -> None:
        self.x = x

    @property
    def x(self) -> int:
        return self._x

    @x.setter
    def x(self, value: int) -> None:
        print(value)
        print("dc Setter is called")
        self._x = value

a = A()
#> <property object at 0x7fa7b2813f60>
#> dc Setter is called
# Weird, the property object is used if no value is provided for x
a = A(x=1)
#> 2
# > dc Setter is called
# Works as expected