Make extensions give AttributeError when they are disabled

This is how the test suite and presumably some other codes detect if
extensions are enabled or not.

This also dynamically updates __all__ whenever extensions are enabled or
disabled.

array_api_strict/__init__.py

@@ -16,13 +16,15 @@
 
 """
 
+__all__ = []
+
 # Warning: __array_api_version__ could change globally with
 # set_array_api_strict_flags(). This should always be accessed as an
 # attribute, like xp.__array_api_version__, or using
 # array_api_strict.get_array_api_strict_flags()['api_version'].
 from ._flags import API_VERSION as __array_api_version__
 
-__all__ = ["__array_api_version__"]
+__all__ += ["__array_api_version__"]
 
 from ._constants import e, inf, nan, pi, newaxis
 
@@ -266,19 +268,10 @@
     "__array_namespace_info__",
 ]
 
-# linalg is an extension in the array API spec, which is a sub-namespace. Only
-# a subset of functions in it are imported into the top-level namespace.
-from . import linalg
-
-__all__ += ["linalg"]
-
 from ._linear_algebra_functions import matmul, tensordot, matrix_transpose, vecdot
 
 __all__ += ["matmul", "tensordot", "matrix_transpose", "vecdot"]
 
-from . import fft
-__all__ += ["fft"]
-
 from ._manipulation_functions import (
     concat,
     expand_dims,
@@ -330,3 +323,22 @@
 from . import _version
 __version__ = _version.get_versions()['version']
 del _version
+
+
+# Extensions can be enabled or disabled dynamically. In order to make
+# "array_api_strict.linalg" give an AttributeError when it is disabled, we
+# use __getattr__. Note that linalg and fft are dynamically added and removed
+# from __all__ in set_array_api_strict_flags.
+
+def __getattr__(name):
+    if name in ['linalg', 'fft']:
+        if name in get_array_api_strict_flags()['enabled_extensions']:
+            if name == 'linalg':
+                from . import _linalg
+                return _linalg
+            elif name == 'fft':
+                from . import _fft
+                return _fft
+        else:
+            raise AttributeError(f"The {name!r} extension has been disabled for array_api_strict")
+    raise AttributeError(f"module {__name__!r} has no attribute {name!r}")

array_api_strict/_flags.py

@@ -161,6 +161,10 @@ def set_array_api_strict_flags(
     else:
         ENABLED_EXTENSIONS = tuple([ext for ext in ENABLED_EXTENSIONS if extension_versions[ext] <= API_VERSION])
 
+    array_api_strict.__all__[:] = sorted(set(ENABLED_EXTENSIONS) |
+                                         set(array_api_strict.__all__) -
+                                         set(default_extensions))
+
 # We have to do this separately or it won't get added as the docstring
 set_array_api_strict_flags.__doc__ = set_array_api_strict_flags.__doc__.format(
     supported_versions=supported_versions,
@@ -321,6 +325,9 @@ def set_flags_from_environment():
         if enabled_extensions == [""]:
             enabled_extensions = []
         set_array_api_strict_flags(enabled_extensions=enabled_extensions)
+    else:
+        # Needed at first import to add linalg and fft to __all__
+        set_array_api_strict_flags(enabled_extensions=default_extensions)
 
 set_flags_from_environment()
 

array_api_strict/tests/test_flags.py

@@ -1,7 +1,15 @@
+import sys
+import subprocess
+
 from .._flags import (set_array_api_strict_flags, get_array_api_strict_flags,
                       reset_array_api_strict_flags)
 from .._info import (capabilities, default_device, default_dtypes, devices,
                      dtypes)
+from .._fft import (fft, ifft, fftn, ifftn, rfft, irfft, rfftn, irfftn, hfft,
+                    ihfft, fftfreq, rfftfreq, fftshift, ifftshift)
+from .._linalg import (cholesky, cross, det, diagonal, eigh, eigvalsh, inv,
+                       matmul, matrix_norm, matrix_power, matrix_rank, matrix_transpose, outer, pinv,
+                       qr, slogdet, solve, svd, svdvals, tensordot, trace, vecdot, vector_norm)
 
 from .. import (asarray, unique_all, unique_counts, unique_inverse,
                 unique_values, nonzero, repeat)
@@ -152,29 +160,29 @@ def test_boolean_indexing():
     pytest.raises(RuntimeError, lambda: a[mask])
 
 linalg_examples = {
-    'cholesky': lambda: xp.linalg.cholesky(xp.eye(3)),
-    'cross': lambda: xp.linalg.cross(xp.asarray([1, 0, 0]), xp.asarray([0, 1, 0])),
-    'det': lambda: xp.linalg.det(xp.eye(3)),
-    'diagonal': lambda: xp.linalg.diagonal(xp.eye(3)),
-    'eigh': lambda: xp.linalg.eigh(xp.eye(3)),
-    'eigvalsh': lambda: xp.linalg.eigvalsh(xp.eye(3)),
-    'inv': lambda: xp.linalg.inv(xp.eye(3)),
-    'matmul': lambda: xp.linalg.matmul(xp.eye(3), xp.eye(3)),
-    'matrix_norm': lambda: xp.linalg.matrix_norm(xp.eye(3)),
-    'matrix_power': lambda: xp.linalg.matrix_power(xp.eye(3), 2),
-    'matrix_rank': lambda: xp.linalg.matrix_rank(xp.eye(3)),
-    'matrix_transpose': lambda: xp.linalg.matrix_transpose(xp.eye(3)),
-    'outer': lambda: xp.linalg.outer(xp.asarray([1, 2, 3]), xp.asarray([4, 5, 6])),
-    'pinv': lambda: xp.linalg.pinv(xp.eye(3)),
-    'qr': lambda: xp.linalg.qr(xp.eye(3)),
-    'slogdet': lambda: xp.linalg.slogdet(xp.eye(3)),
-    'solve': lambda: xp.linalg.solve(xp.eye(3), xp.eye(3)),
-    'svd': lambda: xp.linalg.svd(xp.eye(3)),
-    'svdvals': lambda: xp.linalg.svdvals(xp.eye(3)),
-    'tensordot': lambda: xp.linalg.tensordot(xp.eye(3), xp.eye(3)),
-    'trace': lambda: xp.linalg.trace(xp.eye(3)),
-    'vecdot': lambda: xp.linalg.vecdot(xp.asarray([1, 2, 3]), xp.asarray([4, 5, 6])),
-    'vector_norm': lambda: xp.linalg.vector_norm(xp.asarray([1., 2., 3.])),
+    'cholesky': lambda: cholesky(xp.eye(3)),
+    'cross': lambda: cross(xp.asarray([1, 0, 0]), xp.asarray([0, 1, 0])),
+    'det': lambda: det(xp.eye(3)),
+    'diagonal': lambda: diagonal(xp.eye(3)),
+    'eigh': lambda: eigh(xp.eye(3)),
+    'eigvalsh': lambda: eigvalsh(xp.eye(3)),
+    'inv': lambda: inv(xp.eye(3)),
+    'matmul': lambda: matmul(xp.eye(3), xp.eye(3)),
+    'matrix_norm': lambda: matrix_norm(xp.eye(3)),
+    'matrix_power': lambda: matrix_power(xp.eye(3), 2),
+    'matrix_rank': lambda: matrix_rank(xp.eye(3)),
+    'matrix_transpose': lambda: matrix_transpose(xp.eye(3)),
+    'outer': lambda: outer(xp.asarray([1, 2, 3]), xp.asarray([4, 5, 6])),
+    'pinv': lambda: pinv(xp.eye(3)),
+    'qr': lambda: qr(xp.eye(3)),
+    'slogdet': lambda: slogdet(xp.eye(3)),
+    'solve': lambda: solve(xp.eye(3), xp.eye(3)),
+    'svd': lambda: svd(xp.eye(3)),
+    'svdvals': lambda: svdvals(xp.eye(3)),
+    'tensordot': lambda: tensordot(xp.eye(3), xp.eye(3)),
+    'trace': lambda: trace(xp.eye(3)),
+    'vecdot': lambda: vecdot(xp.asarray([1, 2, 3]), xp.asarray([4, 5, 6])),
+    'vector_norm': lambda: vector_norm(xp.asarray([1., 2., 3.])),
 }
 
 assert set(linalg_examples) == set(xp.linalg.__all__)
@@ -210,20 +218,20 @@ def test_linalg(func_name):
     main_namespace_func()
 
 fft_examples = {
-    'fft': lambda: xp.fft.fft(xp.asarray([0j, 1j, 0j, 0j])),
-    'ifft': lambda: xp.fft.ifft(xp.asarray([0j, 1j, 0j, 0j])),
-    'fftn': lambda: xp.fft.fftn(xp.asarray([[0j, 1j], [0j, 0j]])),
-    'ifftn': lambda: xp.fft.ifftn(xp.asarray([[0j, 1j], [0j, 0j]])),
-    'rfft': lambda: xp.fft.rfft(xp.asarray([0., 1., 0., 0.])),
-    'irfft': lambda: xp.fft.irfft(xp.asarray([0j, 1j, 0j, 0j])),
-    'rfftn': lambda: xp.fft.rfftn(xp.asarray([[0., 1.], [0., 0.]])),
-    'irfftn': lambda: xp.fft.irfftn(xp.asarray([[0j, 1j], [0j, 0j]])),
-    'hfft': lambda: xp.fft.hfft(xp.asarray([0j, 1j, 0j, 0j])),
-    'ihfft': lambda: xp.fft.ihfft(xp.asarray([0., 1., 0., 0.])),
-    'fftfreq': lambda: xp.fft.fftfreq(4),
-    'rfftfreq': lambda: xp.fft.rfftfreq(4),
-    'fftshift': lambda: xp.fft.fftshift(xp.asarray([0j, 1j, 0j, 0j])),
-    'ifftshift': lambda: xp.fft.ifftshift(xp.asarray([0j, 1j, 0j, 0j])),
+    'fft': lambda: fft(xp.asarray([0j, 1j, 0j, 0j])),
+    'ifft': lambda: ifft(xp.asarray([0j, 1j, 0j, 0j])),
+    'fftn': lambda: fftn(xp.asarray([[0j, 1j], [0j, 0j]])),
+    'ifftn': lambda: ifftn(xp.asarray([[0j, 1j], [0j, 0j]])),
+    'rfft': lambda: rfft(xp.asarray([0., 1., 0., 0.])),
+    'irfft': lambda: irfft(xp.asarray([0j, 1j, 0j, 0j])),
+    'rfftn': lambda: rfftn(xp.asarray([[0., 1.], [0., 0.]])),
+    'irfftn': lambda: irfftn(xp.asarray([[0j, 1j], [0j, 0j]])),
+    'hfft': lambda: hfft(xp.asarray([0j, 1j, 0j, 0j])),
+    'ihfft': lambda: ihfft(xp.asarray([0., 1., 0., 0.])),
+    'fftfreq': lambda: fftfreq(4),
+    'rfftfreq': lambda: rfftfreq(4),
+    'fftshift': lambda: fftshift(xp.asarray([0j, 1j, 0j, 0j])),
+    'ifftshift': lambda: ifftshift(xp.asarray([0j, 1j, 0j, 0j])),
 }
 
 assert set(fft_examples) == set(xp.fft.__all__)
@@ -276,3 +284,89 @@ def test_api_version_2023_12(func_name):
 
     set_array_api_strict_flags(api_version='2022.12')
     pytest.raises(RuntimeError, func)
+
+def test_disabled_extensions():
+    # Test that xp.extension errors when an extension is disabled, and that
+    # xp.__all__ is updated properly.
+
+    # First test that things are correct on the initial import. Since we have
+    # already called set_array_api_strict_flags many times throughout running
+    # the tests, we have to test this in a subprocess.
+    subprocess_tests = [('''\
+import array_api_strict
+
+array_api_strict.linalg # No error
+array_api_strict.fft # No error
+assert "linalg" in array_api_strict.__all__
+assert "fft" in array_api_strict.__all__
+assert len(array_api_strict.__all__) == len(set(array_api_strict.__all__))
+''', {}),
+# Test that the initial population of __all__ works correctly
+('''\
+from array_api_strict import * # No error
+linalg # Should have been imported by the previous line
+fft
+''', {}),
+('''\
+from array_api_strict import * # No error
+linalg # Should have been imported by the previous line
+assert 'fft' not in globals()
+''', {"ARRAY_API_STRICT_ENABLED_EXTENSIONS": "linalg"}),
+('''\
+from array_api_strict import * # No error
+fft # Should have been imported by the previous line
+assert 'linalg' not in globals()
+''', {"ARRAY_API_STRICT_ENABLED_EXTENSIONS": "fft"}),
+('''\
+from array_api_strict import * # No error
+assert 'linalg' not in globals()
+assert 'fft' not in globals()
+''', {"ARRAY_API_STRICT_ENABLED_EXTENSIONS": ""}),
+]
+    for test, env in subprocess_tests:
+        try:
+            subprocess.run([sys.executable, '-c', test], check=True,
+                           capture_output=True, encoding='utf-8', env=env)
+        except subprocess.CalledProcessError as e:
+            print(e.stdout, end='')
+            # Ensure the exception is shown in the output log
+            raise AssertionError(e.stderr)
+
+    assert 'linalg' in xp.__all__
+    assert 'fft' in xp.__all__
+    xp.linalg # No error
+    xp.fft # No error
+    ns = {}
+    exec('from array_api_strict import *', ns)
+    assert 'linalg' in ns
+    assert 'fft' in ns
+
+    set_array_api_strict_flags(enabled_extensions=('linalg',))
+    assert 'linalg' in xp.__all__
+    assert 'fft' not in xp.__all__
+    xp.linalg # No error
+    pytest.raises(AttributeError, lambda: xp.fft)
+    ns = {}
+    exec('from array_api_strict import *', ns)
+    assert 'linalg' in ns
+    assert 'fft' not in ns
+
+    set_array_api_strict_flags(enabled_extensions=('fft',))
+    assert 'linalg' not in xp.__all__
+    assert 'fft' in xp.__all__
+    pytest.raises(AttributeError, lambda: xp.linalg)
+    xp.fft # No error
+    ns = {}
+    exec('from array_api_strict import *', ns)
+    assert 'linalg' not in ns
+    assert 'fft' in ns
+
+    set_array_api_strict_flags(enabled_extensions=())
+    assert 'linalg' not in xp.__all__
+    assert 'fft' not in xp.__all__
+    pytest.raises(AttributeError, lambda: xp.linalg)
+    pytest.raises(AttributeError, lambda: xp.fft)
+    ns = {}
+    exec('from array_api_strict import *', ns)
+    assert 'linalg' not in ns
+    assert 'fft' not in ns