"""A module with the precisions of generic `~numpy.number` types."""
from .._utils import set_module
from typing import final
@final # Disallow the creation of arbitrary `NBitBase` subclasses
@set_module("numpy.typing")
class NBitBase:
"""
A type representing `numpy.number` precision during static type checking.
Used exclusively for the purpose static type checking, `NBitBase`
represents the base of a hierarchical set of subclasses.
Each subsequent subclass is herein used for representing a lower level
of precision, *e.g.* ``64Bit > 32Bit > 16Bit``.
.. versionadded:: 1.20
Examples
--------
Below is a typical usage example: `NBitBase` is herein used for annotating
a function that takes a float and integer of arbitrary precision
as arguments and returns a new float of whichever precision is largest
(*e.g.* ``np.float16 + np.int64 -> np.float64``).
.. code-block:: python
>>> from __future__ import annotations
>>> from typing import TypeVar, TYPE_CHECKING
>>> import numpy as np
>>> import numpy.typing as npt
>>> S = TypeVar("S", bound=npt.NBitBase)
>>> T = TypeVar("T", bound=npt.NBitBase)
>>> def add(a: np.floating[S], b: np.integer[T]) -> np.floating[S | T]:
... return a + b
>>> a = np.float16()
>>> b = np.int64()
>>> out = add(a, b)
>>> if TYPE_CHECKING:
... reveal_locals()
... # note: Revealed local types are:
... # note: a: numpy.floating[numpy.typing._16Bit*]
... # note: b: numpy.signedinteger[numpy.typing._64Bit*]
... # note: out: numpy.floating[numpy.typing._64Bit*]
"""
def __init_subclass__(cls) -> None:
allowed_names = {
"NBitBase", "_256Bit", "_128Bit", "_96Bit", "_80Bit",
"_64Bit", "_32Bit", "_16Bit", "_8Bit",
}
if cls.__name__ not in allowed_names:
raise TypeError('cannot inherit from final class "NBitBase"')
super().__init_subclass__()
@final
@set_module("numpy._typing")
# Silence errors about subclassing a `@final`-decorated class
class _256Bit(NBitBase): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _128Bit(_256Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _96Bit(_128Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _80Bit(_96Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _64Bit(_80Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _32Bit(_64Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _16Bit(_32Bit): # type: ignore[misc]
pass
@final
@set_module("numpy._typing")
class _8Bit(_16Bit): # type: ignore[misc]
pass