MAINT: Move aliases for common scalar unions to `numpy.typing` (#17429)

* MAINT: Move the `<scalar>Like` unions to `numpy.typing`

1 files changed, 26 insertions, 0 deletions

diff --git a/numpy/typing/_scalars.py b/numpy/typing/_scalars.py
new file mode 100644
index 000000000..e4fc28b07
--- /dev/null
+++ b/numpy/typing/_scalars.py
@@ -0,0 +1,26 @@
+from typing import Union, Tuple, Any
+
+import numpy as np
+
+# NOTE: `_StrLike` and `_BytesLike` are pointless, as `np.str_` and `np.bytes_`
+# are already subclasses of their builtin counterpart
+
+_CharLike = Union[str, bytes]
+
+_BoolLike = Union[bool, np.bool_]
+_IntLike = Union[int, np.integer]
+_FloatLike = Union[_IntLike, float, np.floating]
+_ComplexLike = Union[_FloatLike, complex, np.complexfloating]
+_NumberLike = Union[int, float, complex, np.number, np.bool_]
+
+_ScalarLike = Union[
+    int,
+    float,
+    complex,
+    str,
+    bytes,
+    np.generic,
+]
+
+# `_VoidLike` is technically not a scalar, but it's close enough
+_VoidLike = Union[Tuple[Any, ...], np.void]