我有一个数据类，它可以接受一个关键字值，或者如果未指定值，则可以从其他属性推断出一个值。
import dataclasses
@dataclasses.dataclass
class RelatedValues:
    primary: float
    _: dataclasses.KW_ONLY
    secondary: float | None = None
def __post_init__(self):
    if self.secondary is None:
        self.secondary = self.primary
这段代码有效，但它让我在`.secondary`的类型提示中被困扰，即使在`__post_init__`之后`.secondary`*绝对不可能*是`None`。
在`__post_init__`中对`self.secondary`进行`cast`操作不起作用。但这个方法起作用：
NULL_FLOAT = float(int(uuid.uuid4())
@dataclasses.dataclass
class RelatedValues:
    primary: float
    _: dataclasses.KW_ONLY
    secondary: float = NULL_FLOAT
def __post_init__(self):
    if self.secondary == NULL_FLOAT:
        self.secondary = self.primary
但这种方法感觉不太符合Python的风格。
以下方法也有效：
@dataclasses.dataclass
class RelatedValues:
    primary: float
    _: dataclasses.KW_ONLY
    _secondary: float | None = None
def __post_init__(self):
    if self._secondary is None:
        self.secondary = self.primary
    else:
        self.secondary = self._secondary
或者这种方法也可以：
@dataclasses.dataclass
class RelatedValues:
    primary: float
    _: dataclasses.KW_ONLY
    _secondary: float | None = None
@property
def secondary(self) -> float:
    if self._secondary is None:
        self.secondary = self.primary
    else:
        self.secondary = self._secondary
但后两种方法只是为了类型缩小而操纵我的kwargs，这种做法有点不太对。
我漏掉了什么？

from dataclasses import dataclass, field, InitVar
@dataclass
class RelatedValues:
    primary: float
    secondary: float = field(init=False)
    secondary_: InitVar[float|None] = None
    def __post_init__(self, secondary_):
        if secondary_ is None:
            secondary_ = self.primary
        self.secondary = secondary_

@dataclass(init=False)
class RelatedValues:
    primary: float
    secondary: float
    def __init__(self, primary: float, secondary: float = None):
        if secondary is None:
            secondary = primary
        self.primary = primary
        self.secondary = secondary