Merge pull request #143 from crusaderky/finfo_iinfo

MAINT: finfo() / iinfo() input/output review

Author: ev-br

array_api_strict/_data_type_functions.py

@@ -100,7 +100,9 @@ def can_cast(from_: DType | Array, to: DType, /) -> bool:
 
 # These are internal objects for the return types of finfo and iinfo, since
 # the NumPy versions contain extra data that isn't part of the spec.
-@dataclass
+# There should be no expectation for them to be comparable, hashable, or writeable.
+
+@dataclass(frozen=True, eq=False)
 class finfo_object:
     bits: int
     # Note: The types of the float data here are float, whereas in NumPy they
@@ -111,22 +113,32 @@ class finfo_object:
     smallest_normal: float
     dtype: DType
 
+    __hash__ = NotImplemented
+
 
-@dataclass
+@dataclass(frozen=True, eq=False)
 class iinfo_object:
     bits: int
     max: int
     min: int
     dtype: DType
 
+    __hash__ = NotImplemented
+
 
 def finfo(type: DType | Array, /) -> finfo_object:
     """
     Array API compatible wrapper for :py:func:`np.finfo <numpy.finfo>`.
 
     See its docstring for more information.
     """
-    np_type = type._array if isinstance(type, Array) else type._np_dtype
+    if isinstance(type, Array):
+        np_type = type._dtype._np_dtype
+    elif isinstance(type, DType):
+        np_type = type._np_dtype
+    else:
+        raise TypeError(f"'type' must be a dtype or array, not {type!r}")
+
     fi = np.finfo(np_type)
     # Note: The types of the float data here are float, whereas in NumPy they
     # are scalars of the corresponding float dtype.
@@ -146,7 +158,13 @@ def iinfo(type: DType | Array, /) -> iinfo_object:
 
     See its docstring for more information.
     """
-    np_type = type._array if isinstance(type, Array) else type._np_dtype
+    if isinstance(type, Array):
+        np_type = type._dtype._np_dtype
+    elif isinstance(type, DType):
+        np_type = type._np_dtype
+    else:
+        raise TypeError(f"'type' must be a dtype or array, not {type!r}")
+
     ii = np.iinfo(np_type)
     return iinfo_object(ii.bits, ii.max, ii.min, DType(ii.dtype))
 

array_api_strict/_dtypes.py

@@ -35,7 +35,7 @@ def __eq__(self, other: object) -> builtins.bool:
                 stacklevel=2,
             )
         if not isinstance(other, DType):
-            return NotImplemented
+            return False
         return self._np_dtype == other._np_dtype
 
     def __hash__(self) -> int:

array_api_strict/tests/test_data_type_functions.py

@@ -1,15 +1,12 @@
 import warnings
 
+import numpy as np
 import pytest
-
 from numpy.testing import assert_raises
-import numpy as np
 
 from .._creation_functions import asarray
-from .._data_type_functions import astype, can_cast, isdtype, result_type
-from .._dtypes import (
-    bool, int8, int16, uint8, float64, int64
-)
+from .._data_type_functions import astype, can_cast, finfo, iinfo, isdtype, result_type
+from .._dtypes import bool, float64, int8, int16, int64, uint8
 from .._flags import set_array_api_strict_flags
 
 
@@ -88,3 +85,40 @@ def test_result_type_py_scalars(api_version):
 
         with pytest.raises(TypeError):
             result_type(int64, True)
+
+
+def test_finfo_iinfo_dtypelike():
+    """np.finfo() and np.iinfo() accept any DTypeLike.
+    Array API only accepts Array | DType.
+    """
+    match = "must be a dtype or array"
+    with pytest.raises(TypeError, match=match):
+        finfo("float64")
+    with pytest.raises(TypeError, match=match):
+        finfo(float)
+    with pytest.raises(TypeError, match=match):
+        iinfo("int8")
+    with pytest.raises(TypeError, match=match):
+        iinfo(int)
+
+
+def test_finfo_iinfo_wrap_output():
+    """Test that the finfo(...).dtype and iinfo(...).dtype
+    are array-api-strict.DType objects; not numpy.dtype.
+    """
+    # Note: array_api_strict.DType objects are not singletons
+    assert finfo(float64).dtype == float64
+    assert iinfo(int8).dtype == int8
+
+
+@pytest.mark.parametrize("func,arg", [(finfo, float64), (iinfo, int8)])
+def test_finfo_iinfo_output_assumptions(func, arg):
+    """There should be no expectation for the output of finfo()/iinfo()
+    to be comparable, hashable, or writeable.
+    """
+    obj = func(arg)
+    assert obj != func(arg)  # Defaut behaviour for custom classes
+    with pytest.raises(TypeError):
+        hash(obj)
+    with pytest.raises(Exception, match="cannot assign"):
+        obj.min = 0