Implement Real and Complex type aliases

The Python standard library `numbers` module defines abstract base
classes for different types of numbers, but those classes are not
suitable for type checking (python/mypy#3186),
so `astropy` should define these types itself.

astropy/units/format/base.py

@@ -8,12 +8,12 @@
 
 if TYPE_CHECKING:
     from collections.abc import Iterable
-    from numbers import Real
     from typing import ClassVar, Literal
 
     import numpy as np
 
     from astropy.units import NamedUnit, UnitBase
+    from astropy.utils.typing import Real
 
 
 class Base:

astropy/units/format/latex.py

@@ -12,10 +12,10 @@
 from . import console, utils
 
 if TYPE_CHECKING:
-    from numbers import Real
     from typing import ClassVar, Literal
 
     from astropy.units import NamedUnit, UnitBase
+    from astropy.utils.typing import Real
 
 
 class Latex(console.Console):

astropy/units/format/unicode_format.py

@@ -11,10 +11,10 @@
 from . import console, utils
 
 if TYPE_CHECKING:
-    from numbers import Real
     from typing import ClassVar
 
     from astropy.units import NamedUnit
+    from astropy.utils.typing import Real
 
 
 class Unicode(console.Console):

astropy/units/format/utils.py

@@ -13,10 +13,10 @@
 
 if TYPE_CHECKING:
     from collections.abc import Callable, Generator, Iterable, Sequence
-    from numbers import Real
     from typing import TypeVar
 
     from astropy.units import UnitBase
+    from astropy.utils.typing import Real
 
     T = TypeVar("T")
 

astropy/units/utils.py

@@ -18,11 +18,12 @@
 
 if TYPE_CHECKING:
     from collections.abc import Generator, Sequence
-    from numbers import Complex, Real
     from typing import Literal, SupportsFloat, TypeVar
 
     from numpy.typing import ArrayLike, NDArray
 
+    from astropy.utils.typing import Complex, Real
+
     from .core import UnitBase
     from .quantity import Quantity
 

astropy/utils/typing.py

@@ -0,0 +1,16 @@
+# Licensed under a 3-clause BSD style license - see LICENSE.rst
+
+"""
+Experimental typing support for ``astropy``, subject to change
+without notice.
+"""
+
+from fractions import Fraction
+from typing import TypeAlias
+
+import numpy as np
+
+# The classes from the standard library `numbers` module are not suitable for
+# type checking (https://github.com/python/mypy/issues/3186).
+Real: TypeAlias = int | float | Fraction | np.integer | np.floating
+Complex: TypeAlias = Real | complex | np.complexfloating

docs/nitpick-exceptions

@@ -83,7 +83,6 @@ py:class a shallow copy of D
 # types
 py:class EllipsisType
 py:class ModuleType
-py:class Real
 # numpy
 py:class np.number
 # numpy.typing