Bugs item #1204734, was opened at 2005-05-19 05:21 Message generated for change (Settings changed) made by gbrandl You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1204734&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Documentation Group: None Status: Closed Resolution: Fixed Priority: 5 Submitted By: John Eikenberry (zhar) >Assigned to: Georg Brandl (gbrandl) Summary: __getattribute__ documentation error? Initial Comment: >From http://www.python.org/dev/doc/devel/ref/new-style-attribute-access.html "Called unconditionally to implement attribute accesses for instances of the class. If the class also defines __getattr__, it will never be called (unless called explicitly)." But I'm not seeing this behaviour in python-2.3.5 and python-2.4.1 on Linux. class A(object): def __getattr__(self,key): print '__getattr__',key raise AttributeError,key def __getattribute__(self,key): print '__getattribute__',key raise AttributeError,key a = A() a.foo $ python test.py __getattribute__ foo __getattr__ foo Traceback (most recent call last): File "test.py", line 14, in ? a.foo File "test.py", line 7, in __getattr__ raise AttributeError(key) AttributeError: foo It seems to be calling __getattribute__ as it should, but then it falls back on __getattr__ even though the docs specifically say it shouldn't. ---------------------------------------------------------------------- Comment By: Georg Brandl (birkenfeld) Date: 2005-07-02 10:30 Message: Logged In: YES user_id=1188172 Checked in my patch as Doc/ref/ref3.tex r1.125, r1.121.2.4. ---------------------------------------------------------------------- Comment By: Georg Brandl (birkenfeld) Date: 2005-06-04 10:03 Message: Logged In: YES user_id=1188172 Attached a documentation patch, following Terry's wording. ---------------------------------------------------------------------- Comment By: Terry J. Reedy (tjreedy) Date: 2005-05-26 17:42 Message: Logged In: YES user_id=593130 If I understand correctly, this revision of the consequent of the second sentence (after ',') matches the implementation. [If the class also defines __getattr__, ] the latter will not be called unless __getattribute__ either calls it explicitly or raises an AttributeError. ---------------------------------------------------------------------- Comment By: Guido van Rossum (gvanrossum) Date: 2005-05-26 16:18 Message: Logged In: YES user_id=6380 The implementation works as expected. The documentation is flawed. ---------------------------------------------------------------------- Comment By: John Eikenberry (zhar) Date: 2005-05-26 15:52 Message: Logged In: YES user_id=322022 Terry, I started with a much longer subject but decided I didn't want to overload it to much. Guess I went to far the other way. I'll try to strike a better balance next time. Thanks. ---------------------------------------------------------------------- Comment By: Terry J. Reedy (tjreedy) Date: 2005-05-26 15:43 Message: Logged In: YES user_id=593130 John E: A general title like 'Documentation Error?' discourages attention from people with the specialized knowledge needed to answer such a question. I have taken the liberty of trying to add '__getattribute__'. We'll see if the edit works when I, not the OP, submits it. ---------------------------------------------------------------------- Comment By: Terry J. Reedy (tjreedy) Date: 2005-05-26 15:33 Message: Logged In: YES user_id=593130 If the default __getattribute__ explicitly calls __getattr__ (but I don't know which source file to check), then the second sentence above *would* make some sense. Guido (or deputy): what is your design intention? Note: if the second sentence is kept, replacing 'it' with 'the latter' would make it clearer. I first read 'it' as referring to __getattribute__. ---------------------------------------------------------------------- Comment By: Armin Rigo (arigo) Date: 2005-05-24 09:08 Message: Logged In: YES user_id=4771 I'll wait for an "authorized" confirmation, but so far I think that the current implementation is really how it is supposed to work. The method 'object.__getattribute__' must be there, given that it is a common technique to use it directly in overridden __getattribute__ implementations. As a consequence, __getattribute__ cannot completely shadow __getattr__, or __getattr__ would never be called. ---------------------------------------------------------------------- Comment By: John Eikenberry (zhar) Date: 2005-05-23 18:43 Message: Logged In: YES user_id=322022 Please specify in the documentation whether this is how it is supposed to work or whether this is a side-effect of the implementation. To make explicit if you can write code relying on this 'feature' and not have it break at some point. ---------------------------------------------------------------------- Comment By: Armin Rigo (arigo) Date: 2005-05-23 14:28 Message: Logged In: YES user_id=4771 Indeed, the logic in typeobject.c is to call __getattribute__ and fall back on __getattr__ if the former raised an AttributeError. This is necessary because all objects have a __getattribute__, actually, as there is one in the 'object' base class. This let me think that the error is really in the documentation, which should mention this logic. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1204734&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
