Bugs item #718532, was opened at 2003-04-09 17:01 Message generated for change (Comment added) made by facundobatista You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=718532&group_id=5470
Category: Python Library Group: Python 2.2.2 Status: Open Resolution: None Priority: 5 Submitted By: Stefan Schwarzer (sschwarzer) Assigned to: Raymond Hettinger (rhettinger) Summary: inspect, class instances and __getattr__ Initial Comment: inspect.isclass(class_instance) fails if the corresponding class uses a "wildcard" implementation of __getattr__. Example: Python 2.2.2 (#1, Nov 13 2002, 22:53:57) [GCC 2.95.4 20020320 [FreeBSD]] on freebsd4 Type "help", "copyright", "credits" or "license" for more information. >>> import inspect >>> class X: ... def __getattr__(self, name): ... if name == 'foo': ... return 1 ... if name == 'bar': ... return 2 ... else: ... return "default" ... >>> x = X() >>> inspect.isclass(x) 1 The problematic expression in inspect.isclass is hasattr(object, '__bases__') which returns a true value. ---------------------------------------------------------------------- Comment By: Facundo Batista (facundobatista) Date: 2005-01-15 14:50 Message: Logged In: YES user_id=752496 Please, could you verify if this problem persists in Python 2.3.4 or 2.4? If yes, in which version? Can you provide a test case? If the problem is solved, from which version? Note that if you fail to answer in one month, I'll close this bug as "Won't fix". Thank you! . Facundo ---------------------------------------------------------------------- Comment By: Raymond Hettinger (rhettinger) Date: 2003-04-15 07:40 Message: Logged In: YES user_id=80475 Ping, if this change is made, will isclass() still be able to find extension classes? The addition of the hasattr(object, '__bases__') was made by you in ver 1.11 about two years ago. ---------------------------------------------------------------------- Comment By: Walter Dörwald (doerwalter) Date: 2003-04-15 07:01 Message: Logged In: YES user_id=89016 type(object) in (types.TypeType, types.ClassType) won't work with custom metaclasses. isinstance(object, (type, types.ClassType)) would be better. ---------------------------------------------------------------------- Comment By: Stefan Schwarzer (sschwarzer) Date: 2003-04-15 05:01 Message: Logged In: YES user_id=383516 Hello Raymond, thanks for your reply. In fact, I'm also not sure if it counts as a bug. I also suggested a patch (handle __getattr__ requests for __bases__ with an AttributeError) for for the SF project which causes/d the problem. I think, if there's a better way to decide on "class-ness" than now, the code in inspect should be changed. Fortunately, it doesn't have to be backward-compatible, because the module is always distributed with a certain interpreter version. ---------------------------------------------------------------------- Comment By: Raymond Hettinger (rhettinger) Date: 2003-04-14 21:36 Message: Logged In: YES user_id=80475 Hmm. I'm not sure that counts as a bug. In an OO language, it's a feature that objects can be made to look like and be substituable for other types. In this case, you've taught your object to be able to fake some classlike behavior (having a __bases__ attribute). OTOH, inspect could have a stronger test for classhood: type(object) in (types.TypeType, types.ClassType) ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=718532&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
