ENH: is_lazy_array and is_writeable_array to return False on non-arrays

array_api_compat/common/_helpers.py

@@ -18,7 +18,7 @@
 import inspect
 import warnings
 
-def _is_jax_zero_gradient_array(x):
+def _is_jax_zero_gradient_array(x: object) -> bool:
     """Return True if `x` is a zero-gradient array.
 
     These arrays are a design quirk of Jax that may one day be removed.
@@ -32,7 +32,8 @@ def _is_jax_zero_gradient_array(x):
 
     return isinstance(x, np.ndarray) and x.dtype == jax.float0
 
-def is_numpy_array(x):
+
+def is_numpy_array(x: object) -> bool:
     """
     Return True if `x` is a NumPy array.
 
@@ -63,7 +64,8 @@ def is_numpy_array(x):
     return (isinstance(x, (np.ndarray, np.generic))
             and not _is_jax_zero_gradient_array(x))
 
-def is_cupy_array(x):
+
+def is_cupy_array(x: object) -> bool:
     """
     Return True if `x` is a CuPy array.
 
@@ -93,7 +95,8 @@ def is_cupy_array(x):
     # TODO: Should we reject ndarray subclasses?
     return isinstance(x, cp.ndarray)
 
-def is_torch_array(x):
+
+def is_torch_array(x: object) -> bool:
     """
     Return True if `x` is a PyTorch tensor.
 
@@ -120,7 +123,8 @@ def is_torch_array(x):
     # TODO: Should we reject ndarray subclasses?
     return isinstance(x, torch.Tensor)
 
-def is_ndonnx_array(x):
+
+def is_ndonnx_array(x: object) -> bool:
     """
     Return True if `x` is a ndonnx Array.
 
@@ -147,7 +151,8 @@ def is_ndonnx_array(x):
 
     return isinstance(x, ndx.Array)
 
-def is_dask_array(x):
+
+def is_dask_array(x: object) -> bool:
     """
     Return True if `x` is a dask.array Array.
 
@@ -174,7 +179,8 @@ def is_dask_array(x):
 
     return isinstance(x, dask.array.Array)
 
-def is_jax_array(x):
+
+def is_jax_array(x: object) -> bool:
     """
     Return True if `x` is a JAX array.
 
@@ -202,6 +208,7 @@ def is_jax_array(x):
 
     return isinstance(x, jax.Array) or _is_jax_zero_gradient_array(x)
 
+
 def is_pydata_sparse_array(x) -> bool:
     """
     Return True if `x` is an array from the `sparse` package.
@@ -231,7 +238,8 @@ def is_pydata_sparse_array(x) -> bool:
     # TODO: Account for other backends.
     return isinstance(x, sparse.SparseArray)
 
-def is_array_api_obj(x):
+
+def is_array_api_obj(x: object) -> bool:
     """
     Return True if `x` is an array API compatible array object.
 
@@ -254,10 +262,12 @@ def is_array_api_obj(x):
         or is_pydata_sparse_array(x) \
         or hasattr(x, '__array_namespace__')
 
-def _compat_module_name():
+
+def _compat_module_name() -> str:
     assert __name__.endswith('.common._helpers')
     return __name__.removesuffix('.common._helpers')
 
+
 def is_numpy_namespace(xp) -> bool:
     """
     Returns True if `xp` is a NumPy namespace.
@@ -278,6 +288,7 @@ def is_numpy_namespace(xp) -> bool:
     """
     return xp.__name__ in {'numpy', _compat_module_name() + '.numpy'}
 
+
 def is_cupy_namespace(xp) -> bool:
     """
     Returns True if `xp` is a CuPy namespace.
@@ -298,6 +309,7 @@ def is_cupy_namespace(xp) -> bool:
     """
     return xp.__name__ in {'cupy', _compat_module_name() + '.cupy'}
 
+
 def is_torch_namespace(xp) -> bool:
     """
     Returns True if `xp` is a PyTorch namespace.
@@ -319,7 +331,7 @@ def is_torch_namespace(xp) -> bool:
     return xp.__name__ in {'torch', _compat_module_name() + '.torch'}
 
 
-def is_ndonnx_namespace(xp):
+def is_ndonnx_namespace(xp) -> bool:
     """
     Returns True if `xp` is an NDONNX namespace.
 
@@ -337,7 +349,8 @@ def is_ndonnx_namespace(xp):
     """
     return xp.__name__ == 'ndonnx'
 
-def is_dask_namespace(xp):
+
+def is_dask_namespace(xp) -> bool:
     """
     Returns True if `xp` is a Dask namespace.
 
@@ -357,7 +370,8 @@ def is_dask_namespace(xp):
     """
     return xp.__name__ in {'dask.array', _compat_module_name() + '.dask.array'}
 
-def is_jax_namespace(xp):
+
+def is_jax_namespace(xp) -> bool:
     """
     Returns True if `xp` is a JAX namespace.
 
@@ -378,7 +392,8 @@ def is_jax_namespace(xp):
     """
     return xp.__name__ in {'jax.numpy', 'jax.experimental.array_api'}
 
-def is_pydata_sparse_namespace(xp):
+
+def is_pydata_sparse_namespace(xp) -> bool:
     """
     Returns True if `xp` is a pydata/sparse namespace.
 
@@ -396,7 +411,8 @@ def is_pydata_sparse_namespace(xp):
     """
     return xp.__name__ == 'sparse'
 
-def is_array_api_strict_namespace(xp):
+
+def is_array_api_strict_namespace(xp) -> bool:
     """
     Returns True if `xp` is an array-api-strict namespace.
 
@@ -414,13 +430,15 @@ def is_array_api_strict_namespace(xp):
     """
     return xp.__name__ == 'array_api_strict'
 
-def _check_api_version(api_version):
+
+def _check_api_version(api_version: str) -> None:
     if api_version in ['2021.12', '2022.12']:
         warnings.warn(f"The {api_version} version of the array API specification was requested but the returned namespace is actually version 2023.12")
     elif api_version is not None and api_version not in ['2021.12', '2022.12',
                                                          '2023.12']:
         raise ValueError("Only the 2023.12 version of the array API specification is currently supported")
 
+
 def array_namespace(*xs, api_version=None, use_compat=None):
     """
     Get the array API compatible namespace for the arrays `xs`.
@@ -808,9 +826,10 @@ def size(x: Array) -> int | None:
     return None if math.isnan(out) else out
 
 
-def is_writeable_array(x) -> bool:
+def is_writeable_array(x: object) -> bool:
     """
     Return False if ``x.__setitem__`` is expected to raise; True otherwise.
+    Return False if `x` is not an array API compatible object.
 
     Warning
     -------
@@ -821,10 +840,10 @@ def is_writeable_array(x) -> bool:
         return x.flags.writeable
     if is_jax_array(x) or is_pydata_sparse_array(x):
         return False
-    return True
+    return is_array_api_obj(x)
 
 
-def is_lazy_array(x) -> bool:
+def is_lazy_array(x: object) -> bool:
     """Return True if x is potentially a future or it may be otherwise impossible or
     expensive to eagerly read its contents, regardless of their size, e.g. by
     calling ``bool(x)`` or ``float(x)``.
@@ -857,6 +876,9 @@ def is_lazy_array(x) -> bool:
     if is_jax_array(x) or is_dask_array(x) or is_ndonnx_array(x):
         return True
 
+    if not is_array_api_obj(x):
+        return False
+
     # Unknown Array API compatible object. Note that this test may have dire consequences
     # in terms of performance, e.g. for a lazy object that eagerly computes the graph
     # on __bool__ (dask is one such example, which however is special-cased above).

tests/test_common.py

@@ -156,6 +156,27 @@ def __bool__(self):
     assert is_lazy_array(x)
 
 
+@pytest.mark.parametrize(
+    'func',
+    list(is_array_functions.values()) 
+    + ["is_array_api_obj", "is_lazy_array", "is_writeable_array"]
+)
+def test_is_array_any_object(func):
+    """Test that is_*_array functions return False and don't raise on non-array objects
+    """
+    func = globals()[func]
+
+    # These objects are missing attributes such as __name__
+    assert not func(object())
+    assert not func(None)
+    assert not func(1)
+
+    class C:
+        pass
+
+    assert not func(C())
+
+
 @pytest.mark.parametrize("library", all_libraries)
 def test_device(library):
     xp = import_(library, wrapper=True)