Fixed bug that ndarrays were considered to be instances of RecArray. (#…

…76)

* Fixed bug that ndarrays were considered to be instances of RecArray.

* Version bump.

Co-authored-by: Ramon <p8u7wAPC5Pg9HYkkCkzA>

HISTORY.md

@@ -1,5 +1,9 @@
 # History
 
+## 2.1.1 (2022-06-01)
+
+- Fixed bug that numpy ndarrays were incorrectly instance checked against `RecArray`.
+
 ## 2.1.0 (2022-06-01)
 
 - Added `Structure` and "structure expressions" to support structured arrays.

README.md

@@ -88,7 +88,8 @@ to express them.
 >>> from nptyping import RecArray
 
 >>> arr = np.array([("Peter", 34)], dtype=[("name", "U10"), ("age", "i4")])
->>> isinstance(arr, RecArray[Any, Structure["name: Str, age: Int"]])
+>>> rec_arr = arr.view(np.recarray)
+>>> isinstance(rec_arr, RecArray[Any, Structure["name: Str, age: Int"]])
 True
 
 ```

nptyping/package_info.py

@@ -22,7 +22,7 @@
 SOFTWARE.
 """
 __title__ = "nptyping"
-__version__ = "2.1.0"
+__version__ = "2.1.1"
 __author__ = "Ramon Hagenaars"
 __author_email__ = "[email protected]"
 __description__ = "Type hints for NumPy."

nptyping/recarray.py

@@ -23,6 +23,8 @@
 """
 from typing import Any, Tuple
 
+import numpy as np
+
 from nptyping.error import InvalidArgumentsError
 from nptyping.ndarray import NDArray, NDArrayMeta
 from nptyping.structure import Structure
@@ -47,6 +49,13 @@ def _get_dtype(cls, dtype_candidate: Any) -> DType:
             )
         return dtype_candidate
 
+    def __instancecheck__(  # pylint: disable=bad-mcs-method-argument
+        self, instance: Any
+    ) -> bool:
+        return isinstance(instance, np.recarray) and NDArrayMeta.__instancecheck__(
+            self, instance
+        )
+
 
 class RecArray(NDArray, metaclass=RecArrayMeta):
     """

tests/test_recarray.py

@@ -16,6 +16,9 @@
 class RecArrayTest(TestCase):
     def test_isinstance_succeeds_if_shape_and_structure_match(self):
         arr = np.array([("William", 23)], dtype=[("name", "U8"), ("age", "i4")])
+
+        self.assertNotIsInstance(arr, RecArray)
+
         rec_arr = arr.view(np.recarray)
 
         self.assertIsInstance(rec_arr, RecArray)