working instancecheck, but not working static analysis

src/numpydantic/exceptions.py

@@ -3,9 +3,25 @@ Exceptions used within numpydantic
 """
 
 
-class DtypeError(TypeError):
+class InterfaceError(Exception):
+    """Parent mixin class for errors raised by :class:`.Interface` subclasses"""
+
+
+class DtypeError(TypeError, InterfaceError):
     """Exception raised for invalid dtypes"""
 
 
-class ShapeError(ValueError):
+class ShapeError(ValueError, InterfaceError):
     """Exception raise for invalid shapes"""
+
+
+class MatchError(ValueError, InterfaceError):
+    """Exception for errors raised during :class:`.Interface.match`-ing"""
+
+
+class NoMatchError(MatchError):
+    """No match was found by :class:`.Interface.match`"""
+
+
+class TooManyMatchesError(MatchError):
+    """Too many matches found by :class:`.Interface.match`"""

src/numpydantic/interface/interface.py

@@ -10,7 +10,12 @@ import numpy as np
 from nptyping.shape_expression import check_shape
 from pydantic import SerializationInfo
 
-from numpydantic.exceptions import DtypeError, ShapeError
+from numpydantic.exceptions import (
+    DtypeError,
+    NoMatchError,
+    ShapeError,
+    TooManyMatchesError,
+)
 from numpydantic.types import DtypeType, NDArrayType, ShapeType
 
 T = TypeVar("T", bound=NDArrayType)
@@ -32,6 +37,25 @@ class Interface(ABC, Generic[T]):
     def validate(self, array: Any) -> T:
         """
         Validate input, returning final array type
+
+        Calls the methods, in order:
+
+        * :meth:`.before_validation`
+        * :meth:`.validate_dtype`
+        * :meth:`.validate_shape`
+        * :meth:`.after_validation`
+
+        passing the ``array`` argument and returning it from each.
+
+        Implementing an interface subclass largely consists of overriding these methods
+        as needed.
+
+        Raises:
+            If validation fails, rather than eg. returning ``False``, exceptions will
+            be raised (to halt the rest of the pydantic validation process).
+            When using interfaces outside of pydantic, you must catch both
+            :class:`.DtypeError` and :class:`.ShapeError` (both of which are children
+            of :class:`.InterfaceError` )
         """
         array = self.before_validation(array)
         array = self.validate_dtype(array)
@@ -150,9 +174,21 @@ class Interface(ABC, Generic[T]):
         return tuple(in_types)
 
     @classmethod
-    def match(cls, array: Any) -> Type["Interface"]:
+    def match(cls, array: Any, fast: bool = False) -> Type["Interface"]:
         """
         Find the interface that should be used for this array based on its input type
+
+        First runs the ``check`` method for all interfaces returned by
+        :meth:`.Interface.interfaces` **except** for :class:`.NumpyInterface` ,
+        and if no match is found then try the numpy interface. This is because
+        :meth:`.NumpyInterface.check` can be expensive, as we could potentially
+        try to
+
+        Args:
+            fast (bool): if ``False`` , check all interfaces and raise exceptions for
+              having multiple matching interfaces (default). If ``True`` ,
+              check each interface (as ordered by its ``priority`` , decreasing),
+              and return on the first match.
         """
         # first try and find a non-numpy interface, since the numpy interface
         # will try and load the array into memory in its check method
@@ -160,17 +196,24 @@ class Interface(ABC, Generic[T]):
         non_np_interfaces = [i for i in interfaces if i.__name__ != "NumpyInterface"]
         np_interface = [i for i in interfaces if i.__name__ == "NumpyInterface"][0]
 
-        matches = [i for i in non_np_interfaces if i.check(array)]
+        if fast:
+            matches = []
+            for i in non_np_interfaces:
+                if i.check(array):
+                    return i
+        else:
+            matches = [i for i in non_np_interfaces if i.check(array)]
+
         if len(matches) > 1:
             msg = f"More than one interface matches input {array}:\n"
             msg += "\n".join([f"  - {i}" for i in matches])
-            raise ValueError(msg)
+            raise TooManyMatchesError(msg)
         elif len(matches) == 0:
             # now try the numpy interface
             if np_interface.check(array):
                 return np_interface
             else:
-                raise ValueError(f"No matching interfaces found for input {array}")
+                raise NoMatchError(f"No matching interfaces found for input {array}")
         else:
             return matches[0]
 
@@ -186,8 +229,8 @@ class Interface(ABC, Generic[T]):
         if len(matches) > 1:
             msg = f"More than one interface matches output {array}:\n"
             msg += "\n".join([f"  - {i}" for i in matches])
-            raise ValueError(msg)
+            raise TooManyMatchesError(msg)
         elif len(matches) == 0:
-            raise ValueError(f"No matching interfaces found for output {array}")
+            raise NoMatchError(f"No matching interfaces found for output {array}")
         else:
             return matches[0]

src/numpydantic/ndarray.py

@@ -13,7 +13,7 @@ Extension of nptyping NDArray for pydantic that allows for JSON-Schema serializa
 
 """
 
-from typing import Any, Tuple
+from typing import TYPE_CHECKING, Any, Tuple
 
 import numpy as np
 from nptyping.error import InvalidArgumentsError
@@ -28,6 +28,8 @@ from pydantic import GetJsonSchemaHandler
 from pydantic_core import core_schema
 
 from numpydantic.dtype import DType
+from numpydantic.exceptions import InterfaceError
+from numpydantic.interface import Interface
 from numpydantic.maps import python_to_nptyping
 from numpydantic.schema import (
     _handler_type,
@@ -37,6 +39,9 @@ from numpydantic.schema import (
 )
 from numpydantic.types import DtypeType, ShapeType
 
+if TYPE_CHECKING:
+    from nptyping.base_meta_classes import SubscriptableMeta
+
 
 class NDArrayMeta(_NDArrayMeta, implementation="NDArray"):
     """
@@ -44,6 +49,35 @@ class NDArrayMeta(_NDArrayMeta, implementation="NDArray"):
     completion of the transition away from nptyping
     """
 
+    if TYPE_CHECKING:
+        __getitem__ = SubscriptableMeta.__getitem__
+
+    def __instancecheck__(self, instance: Any):
+        """
+        Extended type checking that determines whether
+
+        1) the ``type`` of the given instance is one of those in
+            :meth:`.Interface.input_types`
+
+        but also
+
+        2) it satisfies the constraints set on the :class:`.NDArray` annotation
+
+        Args:
+            instance (:class:`typing.Any`): Thing to check!
+
+        Returns:
+            bool: ``True`` if matches constraints, ``False`` otherwise.
+        """
+        shape, dtype = self.__args__
+        try:
+            interface_cls = Interface.match(instance, fast=True)
+            interface = interface_cls(shape, dtype)
+            _ = interface.validate(instance)
+            return True
+        except InterfaceError:
+            return False
+
     def _get_dtype(cls, dtype_candidate: Any) -> DType:
         """
         Override of base _get_dtype method to allow for compound tuple types

src/numpydantic/schema.py

@@ -225,7 +225,9 @@ def get_validate_interface(shape: ShapeType, dtype: DtypeType) -> Callable:
     :meth:`.Interface.validate` method
     """
 
-    def validate_interface(value: Any, info: "ValidationInfo") -> NDArrayType:
+    def validate_interface(
+        value: Any, info: Optional["ValidationInfo"] = None
+    ) -> NDArrayType:
         interface_cls = Interface.match(value)
         interface = interface_cls(shape, dtype)
         value = interface.validate(value)

tests/test_ndarray.py

@@ -223,3 +223,23 @@ def test_json_schema_ellipsis():
 
     schema = ConstrainedAnyShape.model_json_schema()
     _recursive_array(schema)
+
+
+def test_instancecheck():
+    """
+    NDArray should handle ``isinstance()`` s.t. valid arrays are ``True``
+    and invalid arrays are ``False``
+
+    We don't make this test exhaustive because correctness of validation
+    is tested elsewhere. We are just testing that the type checking works
+    """
+    array_type = NDArray[Shape["1, 2, 3"], int]
+
+    assert isinstance(np.zeros((1, 2, 3), dtype=int), array_type)
+    assert not isinstance(np.zeros((2, 2, 3), dtype=int), array_type)
+    assert not isinstance(np.zeros((1, 2, 3), dtype=float), array_type)
+
+    def my_function(array: NDArray[Shape["1, 2, 3"], int]):
+        return array
+
+    my_function(np.zeros((1, 2, 3), int))