From 97c1adf3935234da716d3289b85f72dcd67e90c2 Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Thu, 18 Aug 2016 09:22:23 -0700 Subject: [PATCH] Anti-registration of various ABC methods. - Issue #25958: Support "anti-registration" of special methods from various ABCs, like __hash__, __iter__ or __len__. All these (and several more) can be set to None in an implementation class and the behavior will be as if the method is not defined at all. (Previously, this mechanism existed only for __hash__, to make mutable classes unhashable.) Code contributed by Andrew Barnert and Ivan Levkivskyi. --- Doc/library/collections.abc.rst | 3 +- Doc/reference/datamodel.rst | 19 +++++++- Lib/_collections_abc.py | 78 ++++++++++++--------------------- Lib/test/test_augassign.py | 8 ++++ Lib/test/test_binop.py | 50 ++++++++++++++++++++- Lib/test/test_bool.py | 11 +++++ Lib/test/test_bytes.py | 30 +++++++++++++ Lib/test/test_collections.py | 60 ++++++++++++++++++++++--- Lib/test/test_contains.py | 25 +++++++++++ Lib/test/test_enumerate.py | 9 +++- Lib/test/test_iter.py | 12 +++++ Lib/test/test_unicode.py | 23 ++++++++++ Misc/NEWS | 8 ++++ Objects/enumobject.c | 12 ++++- Objects/typeobject.c | 14 ++++++ 15 files changed, 300 insertions(+), 62 deletions(-) diff --git a/Doc/library/collections.abc.rst b/Doc/library/collections.abc.rst index 3914956496f..6463cea4da8 100644 --- a/Doc/library/collections.abc.rst +++ b/Doc/library/collections.abc.rst @@ -114,7 +114,8 @@ ABC Inherits from Abstract Methods Mixin .. class:: Reversible - ABC for classes that provide the :meth:`__reversed__` method. + ABC for iterable classes that also provide the :meth:`__reversed__` + method. .. versionadded:: 3.6 diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 1b70345b115..08d87cc896c 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -1063,6 +1063,12 @@ to ``type(x).__getitem__(x, i)``. Except where mentioned, attempts to execute a operation raise an exception when no appropriate method is defined (typically :exc:`AttributeError` or :exc:`TypeError`). +Setting a special method to ``None`` indicates that the corresponding +operation is not available. For example, if a class sets +:meth:`__iter__` to ``None``, the class is not iterable, so calling +:func:`iter` on its instances will raise a :exc:`TypeError` (without +falling back to :meth:`__getitem__`). [#]_ + When implementing a class that emulates any built-in type, it is important that the emulation only be implemented to the degree that it makes sense for the object being modelled. For example, some sequences may work well with retrieval @@ -2113,7 +2119,7 @@ left undefined. (``+``, ``-``, ``*``, ``@``, ``/``, ``//``, ``%``, :func:`divmod`, :func:`pow`, ``**``, ``<<``, ``>>``, ``&``, ``^``, ``|``) with reflected (swapped) operands. These functions are only called if the left operand does - not support the corresponding operation and the operands are of different + not support the corresponding operation [#]_ and the operands are of different types. [#]_ For instance, to evaluate the expression ``x - y``, where *y* is an instance of a class that has an :meth:`__rsub__` method, ``y.__rsub__(x)`` is called if ``x.__sub__(y)`` returns *NotImplemented*. @@ -2529,6 +2535,17 @@ An example of an asynchronous context manager class:: controlled conditions. It generally isn't a good idea though, since it can lead to some very strange behaviour if it is handled incorrectly. +.. [#] The :meth:`__hash__`, :meth:`__iter__`, :meth:`__reversed__`, and + :meth:`__contains__` methods have special handling for this; others + will still raise a :exc:`TypeError`, but may do so by relying on + the behavior that ``None`` is not callable. + +.. [#] "Does not support" here means that the class has no such method, or + the method returns ``NotImplemented``. Do not set the method to + ``None`` if you want to force fallback to the right operand's reflected + method--that will instead have the opposite effect of explicitly + *blocking* such fallback. + .. [#] For operands of the same type, it is assumed that if the non-reflected method (such as :meth:`__add__`) fails the operation is not supported, which is why the reflected method is not called. diff --git a/Lib/_collections_abc.py b/Lib/_collections_abc.py index ffee38594fd..077bde4d218 100644 --- a/Lib/_collections_abc.py +++ b/Lib/_collections_abc.py @@ -62,6 +62,18 @@ del _coro ### ONE-TRICK PONIES ### +def _check_methods(C, *methods): + mro = C.__mro__ + for method in methods: + for B in mro: + if method in B.__dict__: + if B.__dict__[method] is None: + return NotImplemented + break + else: + return NotImplemented + return True + class Hashable(metaclass=ABCMeta): __slots__ = () @@ -73,11 +85,7 @@ class Hashable(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Hashable: - for B in C.__mro__: - if "__hash__" in B.__dict__: - if B.__dict__["__hash__"]: - return True - break + return _check_methods(C, "__hash__") return NotImplemented @@ -92,11 +100,7 @@ class Awaitable(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Awaitable: - for B in C.__mro__: - if "__await__" in B.__dict__: - if B.__dict__["__await__"]: - return True - break + return _check_methods(C, "__await__") return NotImplemented @@ -137,14 +141,7 @@ class Coroutine(Awaitable): @classmethod def __subclasshook__(cls, C): if cls is Coroutine: - mro = C.__mro__ - for method in ('__await__', 'send', 'throw', 'close'): - for base in mro: - if method in base.__dict__: - break - else: - return NotImplemented - return True + return _check_methods(C, '__await__', 'send', 'throw', 'close') return NotImplemented @@ -162,8 +159,7 @@ class AsyncIterable(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is AsyncIterable: - if any("__aiter__" in B.__dict__ for B in C.__mro__): - return True + return _check_methods(C, "__aiter__") return NotImplemented @@ -182,9 +178,7 @@ class AsyncIterator(AsyncIterable): @classmethod def __subclasshook__(cls, C): if cls is AsyncIterator: - if (any("__anext__" in B.__dict__ for B in C.__mro__) and - any("__aiter__" in B.__dict__ for B in C.__mro__)): - return True + return _check_methods(C, "__anext__", "__aiter__") return NotImplemented @@ -200,8 +194,7 @@ class Iterable(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Iterable: - if any("__iter__" in B.__dict__ for B in C.__mro__): - return True + return _check_methods(C, "__iter__") return NotImplemented @@ -220,9 +213,7 @@ class Iterator(Iterable): @classmethod def __subclasshook__(cls, C): if cls is Iterator: - if (any("__next__" in B.__dict__ for B in C.__mro__) and - any("__iter__" in B.__dict__ for B in C.__mro__)): - return True + return _check_methods(C, '__iter__', '__next__') return NotImplemented Iterator.register(bytes_iterator) @@ -246,16 +237,13 @@ class Reversible(Iterable): @abstractmethod def __reversed__(self): - return NotImplemented + while False: + yield None @classmethod def __subclasshook__(cls, C): if cls is Reversible: - for B in C.__mro__: - if "__reversed__" in B.__dict__: - if B.__dict__["__reversed__"] is not None: - return True - break + return _check_methods(C, "__reversed__", "__iter__") return NotImplemented @@ -302,17 +290,10 @@ class Generator(Iterator): @classmethod def __subclasshook__(cls, C): if cls is Generator: - mro = C.__mro__ - for method in ('__iter__', '__next__', 'send', 'throw', 'close'): - for base in mro: - if method in base.__dict__: - break - else: - return NotImplemented - return True + return _check_methods(C, '__iter__', '__next__', + 'send', 'throw', 'close') return NotImplemented - Generator.register(generator) @@ -327,8 +308,7 @@ class Sized(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Sized: - if any("__len__" in B.__dict__ for B in C.__mro__): - return True + return _check_methods(C, "__len__") return NotImplemented @@ -343,8 +323,7 @@ class Container(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Container: - if any("__contains__" in B.__dict__ for B in C.__mro__): - return True + return _check_methods(C, "__contains__") return NotImplemented @@ -359,8 +338,7 @@ class Callable(metaclass=ABCMeta): @classmethod def __subclasshook__(cls, C): if cls is Callable: - if any("__call__" in B.__dict__ for B in C.__mro__): - return True + return _check_methods(C, "__call__") return NotImplemented @@ -640,6 +618,8 @@ class Mapping(Sized, Iterable, Container): return NotImplemented return dict(self.items()) == dict(other.items()) + __reversed__ = None + Mapping.register(mappingproxy) diff --git a/Lib/test/test_augassign.py b/Lib/test/test_augassign.py index 5093e9d0f36..5930d9e7a29 100644 --- a/Lib/test/test_augassign.py +++ b/Lib/test/test_augassign.py @@ -83,6 +83,10 @@ class AugAssignTest(unittest.TestCase): def __iadd__(self, val): return aug_test3(self.val + val) + class aug_test4(aug_test3): + """Blocks inheritance, and fallback to __add__""" + __iadd__ = None + x = aug_test(1) y = x x += 10 @@ -106,6 +110,10 @@ class AugAssignTest(unittest.TestCase): self.assertTrue(y is not x) self.assertEqual(x.val, 13) + x = aug_test4(4) + with self.assertRaises(TypeError): + x += 10 + def testCustomMethods2(test_self): output = [] diff --git a/Lib/test/test_binop.py b/Lib/test/test_binop.py index fc8d30fac1f..3ed018e0895 100644 --- a/Lib/test/test_binop.py +++ b/Lib/test/test_binop.py @@ -2,7 +2,7 @@ import unittest from test import support -from operator import eq, le +from operator import eq, le, ne from abc import ABCMeta def gcd(a, b): @@ -388,6 +388,54 @@ class OperationOrderTests(unittest.TestCase): self.assertEqual(op_sequence(eq, B, V), ['B.__eq__', 'V.__eq__']) self.assertEqual(op_sequence(le, B, V), ['B.__le__', 'V.__ge__']) +class SupEq(object): + """Class that can test equality""" + def __eq__(self, other): + return True + +class S(SupEq): + """Subclass of SupEq that should fail""" + __eq__ = None + +class F(object): + """Independent class that should fall back""" + +class X(object): + """Independent class that should fail""" + __eq__ = None + +class SN(SupEq): + """Subclass of SupEq that can test equality, but not non-equality""" + __ne__ = None + +class XN: + """Independent class that can test equality, but not non-equality""" + def __eq__(self, other): + return True + __ne__ = None + +class FallbackBlockingTests(unittest.TestCase): + """Unit tests for None method blocking""" + + def test_fallback_rmethod_blocking(self): + e, f, s, x = SupEq(), F(), S(), X() + self.assertEqual(e, e) + self.assertEqual(e, f) + self.assertEqual(f, e) + # left operand is checked first + self.assertEqual(e, x) + self.assertRaises(TypeError, eq, x, e) + # S is a subclass, so it's always checked first + self.assertRaises(TypeError, eq, e, s) + self.assertRaises(TypeError, eq, s, e) + + def test_fallback_ne_blocking(self): + e, sn, xn = SupEq(), SN(), XN() + self.assertFalse(e != e) + self.assertRaises(TypeError, ne, e, sn) + self.assertRaises(TypeError, ne, sn, e) + self.assertFalse(e != xn) + self.assertRaises(TypeError, ne, xn, e) if __name__ == "__main__": unittest.main() diff --git a/Lib/test/test_bool.py b/Lib/test/test_bool.py index d30a3b9c0f2..5f7e842da2d 100644 --- a/Lib/test/test_bool.py +++ b/Lib/test/test_bool.py @@ -333,6 +333,17 @@ class BoolTest(unittest.TestCase): except (Exception) as e_len: self.assertEqual(str(e_bool), str(e_len)) + def test_blocked(self): + class A: + __bool__ = None + self.assertRaises(TypeError, bool, A()) + + class B: + def __len__(self): + return 10 + __bool__ = None + self.assertRaises(TypeError, bool, B()) + def test_real_and_imag(self): self.assertEqual(True.real, 1) self.assertEqual(True.imag, 0) diff --git a/Lib/test/test_bytes.py b/Lib/test/test_bytes.py index 129b4abf337..64644e7ffba 100644 --- a/Lib/test/test_bytes.py +++ b/Lib/test/test_bytes.py @@ -843,6 +843,36 @@ class BytesTest(BaseBytesTest, unittest.TestCase): self.assertRaises(OverflowError, PyBytes_FromFormat, b'%c', c_int(256)) + def test_bytes_blocking(self): + class IterationBlocked(list): + __bytes__ = None + i = [0, 1, 2, 3] + self.assertEqual(bytes(i), b'\x00\x01\x02\x03') + self.assertRaises(TypeError, bytes, IterationBlocked(i)) + + # At least in CPython, because bytes.__new__ and the C API + # PyBytes_FromObject have different fallback rules, integer + # fallback is handled specially, so test separately. + class IntBlocked(int): + __bytes__ = None + self.assertEqual(bytes(3), b'\0\0\0') + self.assertRaises(TypeError, bytes, IntBlocked(3)) + + # While there is no separately-defined rule for handling bytes + # subclasses differently from other buffer-interface classes, + # an implementation may well special-case them (as CPython 2.x + # str did), so test them separately. + class BytesSubclassBlocked(bytes): + __bytes__ = None + self.assertEqual(bytes(b'ab'), b'ab') + self.assertRaises(TypeError, bytes, BytesSubclassBlocked(b'ab')) + + class BufferBlocked(bytearray): + __bytes__ = None + ba, bb = bytearray(b'ab'), BufferBlocked(b'ab') + self.assertEqual(bytes(ba), b'ab') + self.assertRaises(TypeError, bytes, bb) + class ByteArrayTest(BaseBytesTest, unittest.TestCase): type2test = bytearray diff --git a/Lib/test/test_collections.py b/Lib/test/test_collections.py index c4c0a169fe8..6e858c0d09d 100644 --- a/Lib/test/test_collections.py +++ b/Lib/test/test_collections.py @@ -499,6 +499,9 @@ class ABCTestCase(unittest.TestCase): self.assertTrue(other.right_side,'Right side not called for %s.%s' % (type(instance), name)) +def _test_gen(): + yield + class TestOneTrickPonyABCs(ABCTestCase): def test_Awaitable(self): @@ -686,7 +689,7 @@ class TestOneTrickPonyABCs(ABCTestCase): samples = [bytes(), str(), tuple(), list(), set(), frozenset(), dict(), dict().keys(), dict().items(), dict().values(), - (lambda: (yield))(), + _test_gen(), (x for x in []), ] for x in samples: @@ -700,6 +703,15 @@ class TestOneTrickPonyABCs(ABCTestCase): self.assertFalse(issubclass(str, I)) self.validate_abstract_methods(Iterable, '__iter__') self.validate_isinstance(Iterable, '__iter__') + # Check None blocking + class It: + def __iter__(self): return iter([]) + class ItBlocked(It): + __iter__ = None + self.assertTrue(issubclass(It, Iterable)) + self.assertTrue(isinstance(It(), Iterable)) + self.assertFalse(issubclass(ItBlocked, Iterable)) + self.assertFalse(isinstance(ItBlocked(), Iterable)) def test_Reversible(self): # Check some non-reversibles @@ -707,8 +719,18 @@ class TestOneTrickPonyABCs(ABCTestCase): for x in non_samples: self.assertNotIsInstance(x, Reversible) self.assertFalse(issubclass(type(x), Reversible), repr(type(x))) - # Check some reversibles - samples = [tuple(), list()] + # Check some non-reversible iterables + non_reversibles = [dict().keys(), dict().items(), dict().values(), + Counter(), Counter().keys(), Counter().items(), + Counter().values(), _test_gen(), + (x for x in []), iter([]), reversed([])] + for x in non_reversibles: + self.assertNotIsInstance(x, Reversible) + self.assertFalse(issubclass(type(x), Reversible), repr(type(x))) + # Check some reversible iterables + samples = [bytes(), str(), tuple(), list(), OrderedDict(), + OrderedDict().keys(), OrderedDict().items(), + OrderedDict().values()] for x in samples: self.assertIsInstance(x, Reversible) self.assertTrue(issubclass(type(x), Reversible), repr(type(x))) @@ -725,6 +747,29 @@ class TestOneTrickPonyABCs(ABCTestCase): self.assertEqual(list(reversed(R())), []) self.assertFalse(issubclass(float, R)) self.validate_abstract_methods(Reversible, '__reversed__', '__iter__') + # Check reversible non-iterable (which is not Reversible) + class RevNoIter: + def __reversed__(self): return reversed([]) + class RevPlusIter(RevNoIter): + def __iter__(self): return iter([]) + self.assertFalse(issubclass(RevNoIter, Reversible)) + self.assertFalse(isinstance(RevNoIter(), Reversible)) + self.assertTrue(issubclass(RevPlusIter, Reversible)) + self.assertTrue(isinstance(RevPlusIter(), Reversible)) + # Check None blocking + class Rev: + def __iter__(self): return iter([]) + def __reversed__(self): return reversed([]) + class RevItBlocked(Rev): + __iter__ = None + class RevRevBlocked(Rev): + __reversed__ = None + self.assertTrue(issubclass(Rev, Reversible)) + self.assertTrue(isinstance(Rev(), Reversible)) + self.assertFalse(issubclass(RevItBlocked, Reversible)) + self.assertFalse(isinstance(RevItBlocked(), Reversible)) + self.assertFalse(issubclass(RevRevBlocked, Reversible)) + self.assertFalse(isinstance(RevRevBlocked(), Reversible)) def test_Iterator(self): non_samples = [None, 42, 3.14, 1j, b"", "", (), [], {}, set()] @@ -736,7 +781,7 @@ class TestOneTrickPonyABCs(ABCTestCase): iter(set()), iter(frozenset()), iter(dict().keys()), iter(dict().items()), iter(dict().values()), - (lambda: (yield))(), + _test_gen(), (x for x in []), ] for x in samples: @@ -824,7 +869,7 @@ class TestOneTrickPonyABCs(ABCTestCase): def test_Sized(self): non_samples = [None, 42, 3.14, 1j, - (lambda: (yield))(), + _test_gen(), (x for x in []), ] for x in non_samples: @@ -842,7 +887,7 @@ class TestOneTrickPonyABCs(ABCTestCase): def test_Container(self): non_samples = [None, 42, 3.14, 1j, - (lambda: (yield))(), + _test_gen(), (x for x in []), ] for x in non_samples: @@ -861,7 +906,7 @@ class TestOneTrickPonyABCs(ABCTestCase): def test_Callable(self): non_samples = [None, 42, 3.14, 1j, "", b"", (), [], {}, set(), - (lambda: (yield))(), + _test_gen(), (x for x in []), ] for x in non_samples: @@ -1276,6 +1321,7 @@ class TestCollectionABCs(ABCTestCase): def __iter__(self): return iter(()) self.validate_comparison(MyMapping()) + self.assertRaises(TypeError, reversed, MyMapping()) def test_MutableMapping(self): for sample in [dict]: diff --git a/Lib/test/test_contains.py b/Lib/test/test_contains.py index 3c6bdeffda3..036a1d012db 100644 --- a/Lib/test/test_contains.py +++ b/Lib/test/test_contains.py @@ -84,6 +84,31 @@ class TestContains(unittest.TestCase): self.assertTrue(container == constructor(values)) self.assertTrue(container == container) + def test_block_fallback(self): + # blocking fallback with __contains__ = None + class ByContains(object): + def __contains__(self, other): + return False + c = ByContains() + class BlockContains(ByContains): + """Is not a container + + This class is a perfectly good iterable (as tested by + list(bc)), as well as inheriting from a perfectly good + container, but __contains__ = None prevents the usual + fallback to iteration in the container protocol. That + is, normally, 0 in bc would fall back to the equivalent + of any(x==0 for x in bc), but here it's blocked from + doing so. + """ + def __iter__(self): + while False: + yield None + __contains__ = None + bc = BlockContains() + self.assertFalse(0 in c) + self.assertFalse(0 in list(bc)) + self.assertRaises(TypeError, lambda: 0 in bc) if __name__ == '__main__': unittest.main() diff --git a/Lib/test/test_enumerate.py b/Lib/test/test_enumerate.py index 2630cf2d503..e455adee50f 100644 --- a/Lib/test/test_enumerate.py +++ b/Lib/test/test_enumerate.py @@ -223,7 +223,7 @@ class TestReversed(unittest.TestCase, PickleTest): def test_objmethods(self): # Objects must have __len__() and __getitem__() implemented. class NoLen(object): - def __getitem__(self): return 1 + def __getitem__(self, i): return 1 nl = NoLen() self.assertRaises(TypeError, reversed, nl) @@ -232,6 +232,13 @@ class TestReversed(unittest.TestCase, PickleTest): ngi = NoGetItem() self.assertRaises(TypeError, reversed, ngi) + class Blocked(object): + def __getitem__(self, i): return 1 + def __len__(self): return 2 + __reversed__ = None + b = Blocked() + self.assertRaises(TypeError, reversed, b) + def test_pickle(self): for data in 'abc', range(5), tuple(enumerate('abc')), range(1,17,5): self.check_pickle(reversed(data), list(data)[::-1]) diff --git a/Lib/test/test_iter.py b/Lib/test/test_iter.py index a91670b4a11..542b28419e2 100644 --- a/Lib/test/test_iter.py +++ b/Lib/test/test_iter.py @@ -54,6 +54,14 @@ class UnlimitedSequenceClass: def __getitem__(self, i): return i +class DefaultIterClass: + pass + +class NoIterClass: + def __getitem__(self, i): + return i + __iter__ = None + # Main test suite class TestCase(unittest.TestCase): @@ -995,6 +1003,10 @@ class TestCase(unittest.TestCase): def test_free_after_iterating(self): check_free_after_iterating(self, iter, SequenceClass, (0,)) + def test_error_iter(self): + for typ in (DefaultIterClass, NoIterClass): + self.assertRaises(TypeError, iter, typ()) + def test_main(): run_unittest(TestCase) diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py index a38e7b16104..78f9668e19e 100644 --- a/Lib/test/test_unicode.py +++ b/Lib/test/test_unicode.py @@ -986,6 +986,19 @@ class UnicodeTest(string_tests.CommonTest, def __format__(self, format_spec): return int.__format__(self * 2, format_spec) + class M: + def __init__(self, x): + self.x = x + def __repr__(self): + return 'M(' + self.x + ')' + __str__ = None + + class N: + def __init__(self, x): + self.x = x + def __repr__(self): + return 'N(' + self.x + ')' + __format__ = None self.assertEqual(''.format(), '') self.assertEqual('abc'.format(), 'abc') @@ -1200,6 +1213,16 @@ class UnicodeTest(string_tests.CommonTest, self.assertEqual("0x{:0{:d}X}".format(0x0,16), "0x0000000000000000") + # Blocking fallback + m = M('data') + self.assertEqual("{!r}".format(m), 'M(data)') + self.assertRaises(TypeError, "{!s}".format, m) + self.assertRaises(TypeError, "{}".format, m) + n = N('data') + self.assertEqual("{!r}".format(n), 'N(data)') + self.assertEqual("{!s}".format(n), 'N(data)') + self.assertRaises(TypeError, "{}".format, n) + def test_format_map(self): self.assertEqual(''.format_map({}), '') self.assertEqual('a'.format_map({}), 'a') diff --git a/Misc/NEWS b/Misc/NEWS index 2cd61e64053..b7194bd8f42 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -73,6 +73,14 @@ Core and Builtins Library ------- +- Issue #25958: Support "anti-registration" of special methods from + various ABCs, like __hash__, __iter__ or __len__. All these (and + several more) can be set to None in an implementation class and the + behavior will be as if the method is not defined at all. + (Previously, this mechanism existed only for __hash__, to make + mutable classes unhashable.) Code contributed by Andrew Barnert and + Ivan Levkivskyi. + - Issue #16764: Support keyword arguments to zlib.decompress(). Patch by Xiang Zhang. diff --git a/Objects/enumobject.c b/Objects/enumobject.c index c458cfe73dd..dae166d5adf 100644 --- a/Objects/enumobject.c +++ b/Objects/enumobject.c @@ -250,6 +250,13 @@ reversed_new(PyTypeObject *type, PyObject *args, PyObject *kwds) return NULL; reversed_meth = _PyObject_LookupSpecial(seq, &PyId___reversed__); + if (reversed_meth == Py_None) { + Py_DECREF(reversed_meth); + PyErr_Format(PyExc_TypeError, + "'%.200s' object is not reversible", + Py_TYPE(seq)->tp_name); + return NULL; + } if (reversed_meth != NULL) { PyObject *res = PyObject_CallFunctionObjArgs(reversed_meth, NULL); Py_DECREF(reversed_meth); @@ -259,8 +266,9 @@ reversed_new(PyTypeObject *type, PyObject *args, PyObject *kwds) return NULL; if (!PySequence_Check(seq)) { - PyErr_SetString(PyExc_TypeError, - "argument to reversed() must be a sequence"); + PyErr_Format(PyExc_TypeError, + "'%.200s' object is not reversible", + Py_TYPE(seq)->tp_name); return NULL; } diff --git a/Objects/typeobject.c b/Objects/typeobject.c index b1686d258b0..1b4c2613b59 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -5856,6 +5856,13 @@ slot_sq_contains(PyObject *self, PyObject *value) _Py_IDENTIFIER(__contains__); func = lookup_maybe(self, &PyId___contains__); + if (func == Py_None) { + Py_DECREF(func); + PyErr_Format(PyExc_TypeError, + "'%.200s' object is not a container", + Py_TYPE(self)->tp_name); + return -1; + } if (func != NULL) { args = PyTuple_Pack(1, value); if (args == NULL) @@ -6241,6 +6248,13 @@ slot_tp_iter(PyObject *self) _Py_IDENTIFIER(__iter__); func = lookup_method(self, &PyId___iter__); + if (func == Py_None) { + Py_DECREF(func); + PyErr_Format(PyExc_TypeError, + "'%.200s' object is not iterable", + Py_TYPE(self)->tp_name); + return NULL; + } if (func != NULL) { PyObject *args; args = res = PyTuple_New(0);