ENH: Make numpy.iinfo and numpy.finfo generic at runtime

Author: jorenham

numpy/_core/getlimits.py

@@ -3,6 +3,7 @@
 """
 __all__ = ['finfo', 'iinfo']
 
+import types
 import warnings
 
 from .._utils import set_module
@@ -487,6 +488,8 @@ class finfo:
 
     _finfo_cache = {}
 
+    __class_getitem__ = classmethod(types.GenericAlias)
+
     def __new__(cls, dtype):
         try:
             obj = cls._finfo_cache.get(dtype)  # most common path
@@ -689,6 +692,8 @@ class iinfo:
     _min_vals = {}
     _max_vals = {}
 
+    __class_getitem__ = classmethod(types.GenericAlias)
+
     def __init__(self, int_type):
         try:
             self.dtype = numeric.dtype(int_type)

numpy/_core/tests/test_getlimits.py

@@ -1,6 +1,7 @@
 """ Test functions for limits module.
 
 """
+import types
 import warnings
 import numpy as np
 import pytest
@@ -192,3 +193,11 @@ def test_plausible_finfo():
         assert_(info.nmant > 1)
         assert_(info.minexp < -1)
         assert_(info.maxexp > 1)
+
+
+class TestRuntimeSubscriptable:
+    def test_finfo_generic(self):
+        assert isinstance(np.finfo[np.float64], types.GenericAlias)
+
+    def test_iinfo_generic(self):
+        assert isinstance(np.iinfo[np.int_], types.GenericAlias)