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bpo-20092: Make __int__ defaults to __index__ #13106

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bpo-20092: Make __int__ defaults to __index__ #13106

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a7a1729
Test that __int__ defaults to __index__
May 6, 2019
9ba4d39
Make __int__ defaults to __index__
May 6, 2019
bf39c88
Check PyErr_Occurred only when the result of _PyDict_GetItemIdWithErr…
May 16, 2019
d9a8925
Make tp_int slot default to tp_int
May 17, 2019
44ed7c5
Use only slots
May 19, 2019
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6 changes: 2 additions & 4 deletions Doc/reference/datamodel.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -2389,10 +2389,8 @@ left undefined.

.. note::

In order to have a coherent integer type class, when :meth:`__index__` is
defined :meth:`__int__` should also be defined, and both should return
the same value.

If :meth:`__index__` is defined and not :meth:`__int__`, :meth:`__int__`
automatically defaults to :meth:`__index__`.

.. method:: object.__round__(self, [,ndigits])
object.__trunc__(self)
Expand Down
9 changes: 8 additions & 1 deletion Lib/test/test_index.py
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Expand Up @@ -60,7 +60,7 @@ def test_int_subclass_with_index(self):
# subclasses. See issue #17576.
class MyInt(int):
def __index__(self):
return int(self) + 1
return self + 1

my_int = MyInt(7)
direct_index = my_int.__index__()
Expand Down Expand Up @@ -89,6 +89,13 @@ def __index__(self):
n = operator.index(bad_int)
self.assertEqual(n, 0)

def test_int_defaults_to_index(self):
class Test:
def __index__(self):
return 4

self.assertEqual(int(Test()), 4)


class SeqTestCase:
# This test case isn't run directly. It just defines common tests
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Core and Builtins/2019-05-06-16-00-50.bpo-33039.5YKYPc.rst
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@@ -0,0 +1,2 @@
:meth:`__int__` defaults to :meth:`__index__` when only the latter is
defined. Patch contributed by Rémi Lapeyre.
13 changes: 11 additions & 2 deletions Objects/typeobject.c
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Expand Up @@ -5393,8 +5393,9 @@ PyType_Ready(PyTypeObject *type)
}
}

/* Hack for tp_hash and __hash__.
If after all that, tp_hash is still NULL, and __hash__ is not in
/* Set default methods */

/* If after all that, tp_hash is still NULL, and __hash__ is not in
tp_dict, set tp_hash to PyObject_HashNotImplemented and
tp_dict['__hash__'] equal to None.
This signals that __hash__ is not inherited.
Expand Down Expand Up @@ -5435,6 +5436,14 @@ PyType_Ready(PyTypeObject *type)
goto error;
}

/* If __index__ is defined but not __int__, make it default to __index__.
Don't touch __float__ and __complex__ as there could be some loss of
precision.
*/
if (type->tp_as_number != NULL && type->tp_as_number->nb_int == NULL) {
type->tp_as_number->nb_int = type->tp_as_number->nb_index;
}

/* All done -- set the ready flag */
type->tp_flags =
(type->tp_flags & ~Py_TPFLAGS_READYING) | Py_TPFLAGS_READY;
Expand Down