Type-hint conventions

AxsDB targets Python 3.9+. The rules below keep annotations consistent across the codebase and avoid deprecated typing shims.

from __future__ import annotations

Every module that carries type annotations must open with:

from __future__ import annotations

This makes all annotations strings at runtime, which is what allows the remaining rules to work on Python 3.9 without runtime errors.

Built-in generics

Use lowercase built-in types as generics directly, e.g.:

dict[str, int]
list[float]
tuple[np.ndarray, np.ndarray]
set[str]

Avoid importing typing‘s Dict, List, Tuple, or Set.

Union and None

Use the pipe operator for all unions and for optional types:

float | tuple[float, float]      # not Union[float, Tuple[float, float]]
ErrorHandlingConfiguration | None  # not Optional[ErrorHandlingConfiguration]
Abstract container types

Import abstract base classes from collections.abc, not typing:

from collections.abc import Callable, Hashable, Mapping, Sequence
Class-object annotations

Use lowercase type[X] instead of typing.Type[X]:

AbsorptionDatabaseT = type[AbsorptionDatabase]   # inside TYPE_CHECKING block
Permitted typing imports

The following names have no built-in or collections.abc equivalent and are the only items that should appear in a from typing import … line:

  • Any

  • Annotated

  • Literal

  • TypeAlias

  • TypeVar

  • TYPE_CHECKING

Tests

Test functions and methods do not carry type annotations. Helpers might, but this is not required.