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Merged
merged 3 commits into from
Oct 8, 2018
Merged

ENH: Validate dispatcher functions in array_function_dispatch #12099

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6cc0342
Validate dispatcher functions in array_function_dispatch
shoyer Oct 2, 2018
2f1caf2
ENH: make signature checking in array_function_dispatch optional
shoyer Oct 6, 2018
7bd71e5
Change verify_signature keyword argument to verify
shoyer Oct 8, 2018
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37 changes: 36 additions & 1 deletion numpy/core/overrides.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,11 @@

TODO: rewrite this in C for performance.
"""
import collections
import functools

from numpy.core.multiarray import ndarray
from numpy.compat._inspect import getargspec


_NDARRAY_ARRAY_FUNCTION = ndarray.__array_function__
Expand Down Expand Up @@ -107,13 +110,45 @@ def array_function_implementation_or_override(
.format(public_api, list(map(type, overloaded_args))))


def array_function_dispatch(dispatcher):
ArgSpec = collections.namedtuple('ArgSpec', 'args varargs keywords defaults')


def verify_matching_signatures(implementation, dispatcher):
"""Verify that a dispatcher function has the right signature."""
implementation_spec = ArgSpec(*getargspec(implementation))
dispatcher_spec = ArgSpec(*getargspec(dispatcher))

if (implementation_spec.args != dispatcher_spec.args or
implementation_spec.varargs != dispatcher_spec.varargs or
implementation_spec.keywords != dispatcher_spec.keywords or
(bool(implementation_spec.defaults) !=
bool(dispatcher_spec.defaults)) or
(implementation_spec.defaults is not None and
len(implementation_spec.defaults) !=
len(dispatcher_spec.defaults))):
raise RuntimeError('implementation and dispatcher for %s have '
'different function signatures' % implementation)

if implementation_spec.defaults is not None:
if dispatcher_spec.defaults != (None,) * len(dispatcher_spec.defaults):
raise RuntimeError('dispatcher functions can only use None for '
'default argument values')


def array_function_dispatch(dispatcher, verify=True):
"""Decorator for adding dispatch with the __array_function__ protocol."""
def decorator(implementation):
# TODO: only do this check when the appropriate flag is enabled or for
# a dev install. We want this check for testing but don't want to
# slow down all numpy imports.
if verify:
verify_matching_signatures(implementation, dispatcher)

@functools.wraps(implementation)
def public_api(*args, **kwargs):
relevant_args = dispatcher(*args, **kwargs)
return array_function_implementation_or_override(
implementation, public_api, relevant_args, args, kwargs)
return public_api

return decorator
33 changes: 32 additions & 1 deletion numpy/core/tests/test_overrides.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,8 @@
from numpy.testing import (
assert_, assert_equal, assert_raises, assert_raises_regex)
from numpy.core.overrides import (
get_overloaded_types_and_args, array_function_dispatch)
get_overloaded_types_and_args, array_function_dispatch,
verify_matching_signatures)


def _get_overloaded_args(relevant_args):
Expand Down Expand Up @@ -200,6 +201,36 @@ def __array_function__(self, func, types, args, kwargs):
dispatched_one_arg(array)


class TestVerifyMatchingSignatures(object):

def test_verify_matching_signatures(self):

verify_matching_signatures(lambda x: 0, lambda x: 0)
verify_matching_signatures(lambda x=None: 0, lambda x=None: 0)
verify_matching_signatures(lambda x=1: 0, lambda x=None: 0)

with assert_raises(RuntimeError):
verify_matching_signatures(lambda a: 0, lambda b: 0)
with assert_raises(RuntimeError):
verify_matching_signatures(lambda x: 0, lambda x=None: 0)
with assert_raises(RuntimeError):
verify_matching_signatures(lambda x=None: 0, lambda y=None: 0)
with assert_raises(RuntimeError):
verify_matching_signatures(lambda x=1: 0, lambda y=1: 0)

def test_array_function_dispatch(self):

with assert_raises(RuntimeError):
@array_function_dispatch(lambda x: (x,))
def f(y):
pass

# should not raise
@array_function_dispatch(lambda x: (x,), verify=False)
def f(y):
pass


def _new_duck_type_and_implements():
"""Create a duck array type and implements functions."""
HANDLED_FUNCTIONS = {}
Expand Down