I'm not happy with this fix. Admittedly code like: class S(str): __getattr__ = str.__add__ s = S('a') print(S.b) is a little weird. But I think it should work (ie print 'ab') properly. This works without the patch. class S(str): __getattribute__ = str.__add__ s = S('a') print(S.b) (Prints 'ab') Also "slot wrapper" is a low-level implementation detail and shouldn't impact the language semantics. dict.__getitem__ is a slot wrapper; dict.__getitem__ is not. str.__getitem__ is a slot wrapper; list.__getitem__ is not. If any of these change then the semantics of the language changes. Cheers, Mark benjamin.peterson wrote:

http://hg.python.org/cpython/rev/971865f12377 changeset: 76518:971865f12377 branch: 3.2 parent: 76506:f7b002e5cac7 user: Benjamin Peterson <benjamin@python.org> date: Tue Apr 24 11:06:25 2012 -0400 summary: don't use a slot wrapper from a different special method (closes #14658)

This also alters the fix to #11603. Specifically, setting __repr__ to object.__str__ now raises a recursion RuntimeError when str() or repr() is called instead of silently bypassing the recursion. I believe this behavior is more correct.

files: Lib/test/test_descr.py | 10 +++++++++- Misc/NEWS | 6 ++++++ Objects/typeobject.c | 5 +++-- 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/Lib/test/test_descr.py b/Lib/test/test_descr.py --- a/Lib/test/test_descr.py +++ b/Lib/test/test_descr.py @@ -4430,7 +4430,15 @@ pass Foo.__repr__ = Foo.__str__ foo = Foo() - str(foo) + self.assertRaises(RuntimeError, str, foo) + self.assertRaises(RuntimeError, repr, foo) + + def test_mixing_slot_wrappers(self): + class X(dict): + __setattr__ = dict.__setitem__ + x = X() + x.y = 42 + self.assertEqual(x["y"], 42)

def test_cycle_through_dict(self): # See bug #1469629 diff --git a/Misc/NEWS b/Misc/NEWS --- a/Misc/NEWS +++ b/Misc/NEWS @@ -10,6 +10,12 @@ Core and Builtins -----------------

+- Issue #11603 (again): Setting __repr__ to __str__ now raises a RuntimeError + when repr() or str() is called on such an object. + +- Issue #14658: Fix binding a special method to a builtin implementation of a + special method with a different name. + - Issue #14630: Fix a memory access bug for instances of a subclass of int with value 0.

diff --git a/Objects/typeobject.c b/Objects/typeobject.c --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -2928,7 +2928,7 @@ unaryfunc f;

f = Py_TYPE(self)->tp_repr; - if (f == NULL || f == object_str) + if (f == NULL) f = object_repr; return f(self); } @@ -5757,7 +5757,8 @@ } continue; } - if (Py_TYPE(descr) == &PyWrapperDescr_Type) { + if (Py_TYPE(descr) == &PyWrapperDescr_Type && + ((PyWrapperDescrObject *)descr)->d_base->name_strobj == p->name_strobj) { void **tptr = resolve_slotdups(type, p->name_strobj); if (tptr == NULL || tptr == ptr) generic = p->function;

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