-
-
Notifications
You must be signed in to change notification settings - Fork 3k
Open
Labels
bugmypy got something wrongmypy got something wrong
Description
I am having issues with frozen dataclass that inherits from a frozen dataclass with descriptors as attributes. mypy infer incorrect datatypes of the attributes from the base class. If the dataclasses are not frozen, then mypy infer correct datatypes in inherited class.
Below is the minimal code to reproduce the issue.
python=3.11
mypy=1.14.0
To Reproduce
from abc import ABCMeta, abstractmethod
from dataclasses import dataclass
from typing import Self, SupportsFloat, TypeVar, overload, Type, Optional, Generic, Any
T = TypeVar("T")
V = TypeVar("V")
class Base(Generic[T, V], metaclass=ABCMeta):
def __set_name__(self, owner: type, name: str) -> None:
self.public_name = name
self.private_name = "_" + name
@overload
def __get__(self, instance: None, owner: Optional[Type[Any]] = None) -> Self:...
@overload
def __get__(self, instance: Any, owner: Optional[Type[Any]] = None) -> V | None:...
def __get__(self, instance: Any, owner: Optional[Type[Any]] = None) -> Self | V | None:
if instance is None:
return self
return getattr(instance, self.private_name, None)
def __set__(self, instance: Any, value: Optional[T]) -> None:
if value is self or value is None:
return
converted = self._converter(value)
object.__setattr__(instance, self.private_name, converted)
@abstractmethod
def _converter(self, value: T) -> V:
"""
Hook to implement conversion logic
"""
class FloatParameter(Base[SupportsFloat, float]):
def _converter(self, value: SupportsFloat) -> float:
"""Can have more logic here to check if value can be converted to float"""
return float(value)
@dataclass(frozen=True, kw_only=True)
class BaseDataClass:
float_param: FloatParameter = FloatParameter()
@dataclass(frozen=True, kw_only=True)
class DerivedDataClass(BaseDataClass):
boolean: bool = True
reveal_type(BaseDataClass.float_param) # correct FloatParameter
reveal_type(DerivedDataClass.float_param) # Incorrect Union[typing.SupportsFloat, None]
reveal_type(BaseDataClass().float_param) # Correct "Union[builtins.float, None]"
reveal_type(DerivedDataClass().float_param) # Incorrect Union[typing.SupportsFloat, None]
NOTE: Pylance on the other hand on VSCode shows correct datatypes.
Metadata
Metadata
Assignees
Labels
bugmypy got something wrongmypy got something wrong