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 <benja...@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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