This issue tracker has been migrated to GitHub ,
and is currently read-only.
For more information,
see the GitHub FAQs in the Python's Developer Guide.
Created on 2003年08月05日 14:19 by grodr, last changed 2022年04月10日 16:10 by admin. This issue is now closed.
| Files | ||||
|---|---|---|---|---|
| File name | Uploaded | Description | Edit | |
| OP_example.py | ajaksu2, 2009年02月13日 04:00 | OP's example, cleaned up | ||
| Messages (3) | |||
|---|---|---|---|
| msg60365 - (view) | Author: Gonçalo Rodrigues (grodr) | Date: 2003年08月05日 14:19 | |
Consider the following scenario of property overriding:
>>> class Test(object):
... def __init__(self, n):
... self.__n = n
... #Properties.
... def __get_n(self):
... return self.__n
... def __set_n(self, n):
... self.__n = n
... n = property(__get_n, __set_n)
...
>>> a = Test(42)
>>> a.n
42
>>> a.n = 32
>>> a.n
32
Now, let us override the n property:
>>> class Test2(Test):
... def __init__(self, n):
... super(Test2, self).__init__(n)
... #Properties.
... def __get_n(self):
... return "got ya!"
... def __set_n(self, value):
... print "No way, jose!"
... n = property(__get_n, __set_n)
...
>>> a = Test2(42)
>>> a.n
'got ya!'
>>> a.n = 0
No way, jose!
>>> a.n
'got ya!'
>>> super(Test2, a).n
42
So far so good, super is working well with properties. But
now consider the following inconsistencies:
>>> super(Test2, a).__getattribute__('n')
'got ya!'
>>> super(Test2, a).n
42
Also:
>>> super(Test, Test2).__getattribute__('n')
<property object at 0x01103300>
>>> super(Test, Test2).__getattribute__('n').__get__(a)
'got ya!'
>>> super(Test, Test2).n
Traceback (most recent call last):
File "<interactive input>", line 1, in ?
AttributeError: 'super' object has no attribute 'n'
The last one is particularly damaging, because:
>>> super(Test2, a).n = 32
Traceback (most recent call last):
File "<interactive input>", line 1, in ?
AttributeError: 'super' object has no attribute 'n'
I think the above should work, but whatever’s the
answer, together with the super(Test, Test2) odd
results it does make impossible using super and setting
properties together.
Tested with the latest Python 2.3 in win2k.
With my best regards,
G. Rodrigues
P.S: bug 729913 talks of similar issues at the end: super
does not seem to intercept special methods.
|
|||
| msg81870 - (view) | Author: Daniel Diniz (ajaksu2) * (Python triager) | Date: 2009年02月13日 04:00 | |
Same behavior, is this a real issue? Current exception: TypeError: 'super' object has only read-only attributes (assign to .n) |
|||
| msg114254 - (view) | Author: Mark Lawrence (BreamoreBoy) * | Date: 2010年08月18日 17:27 | |
Closed as no response to msg81870. |
|||
| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022年04月10日 16:10:29 | admin | set | github: 39013 |
| 2013年02月24日 01:08:24 | r.david.murray | set | status: open -> closed superseder: super() and property inheritance behavior resolution: duplicate stage: test needed -> resolved |
| 2010年08月18日 17:27:32 | BreamoreBoy | set | nosy:
+ BreamoreBoy messages: + msg114254 |
| 2009年02月13日 04:00:50 | ajaksu2 | set | files:
+ OP_example.py versions: + Python 2.7, - Python 2.3 nosy: + ajaksu2 messages: + msg81870 type: behavior stage: test needed |
| 2003年08月05日 14:19:12 | grodr | create | |