Only set slots on 3.11+

This works around an issue in `typing`'s handling of generics.

Author: RealOrangeOne

django_tasks/backends/database/backend.py

@@ -6,6 +6,7 @@
 from django.core import checks
 from django.core.exceptions import ValidationError
 from django.db import transaction
+from django.utils.version import PY311
 from typing_extensions import ParamSpec
 
 from django_tasks.backends.base import BaseTaskBackend
@@ -21,7 +22,7 @@
 P = ParamSpec("P")
 
 
-@dataclass(frozen=True, slots=True, kw_only=True)
+@dataclass(frozen=True, slots=PY311, kw_only=True)  # type: ignore[literal-required]
 class TaskResult(BaseTaskResult[T]):
     db_result: "DBTaskResult"
 

django_tasks/base.py

@@ -17,6 +17,7 @@
 from django.db.models.enums import TextChoices
 from django.utils.module_loading import import_string
 from django.utils.translation import pgettext_lazy
+from django.utils.version import PY311
 from typing_extensions import ParamSpec, Self
 
 from .exceptions import TaskIntegrityError
@@ -64,7 +65,7 @@ class ResultStatus(TextChoices):
 P = ParamSpec("P")
 
 
-@dataclass(frozen=True, slots=True, kw_only=True)
+@dataclass(frozen=True, slots=PY311, kw_only=True)  # type: ignore[literal-required]
 class Task(Generic[P, T]):
     priority: int
     """The Task's priority"""
@@ -252,7 +253,7 @@ def wrapper(f: Callable[P, T]) -> Task[P, T]:
     return wrapper
 
 
-@dataclass(frozen=True, slots=True, kw_only=True)
+@dataclass(frozen=True, slots=PY311, kw_only=True)  # type: ignore[literal-required]
 class TaskError:
     exception_class_path: str
     traceback: str
@@ -272,7 +273,7 @@ def exception_class(self) -> type[BaseException]:
         return exception_class
 
 
-@dataclass(frozen=True, slots=True, kw_only=True)
+@dataclass(frozen=True, slots=PY311, kw_only=True)  # type: ignore[literal-required]
 class TaskResult(Generic[T]):
     task: Task
     """Task for which this is a result"""
@@ -359,7 +360,7 @@ async def arefresh(self) -> None:
             object.__setattr__(self, attr, getattr(refreshed_task, attr))
 
 
-@dataclass(frozen=True, slots=True, kw_only=True)
+@dataclass(frozen=True, slots=PY311, kw_only=True)  # type: ignore[literal-required]
 class TaskContext:
     task_result: TaskResult