| msg15412 - (view) |
Author: Stefan Schwarzer (sschwarzer) |
Date: 2003-04-09 20:01 |
| 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. |
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| msg15413 - (view) |
Author: Raymond Hettinger (rhettinger) *  |
Date: 2003-04-15 00:36 |
| 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) |
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| msg15414 - (view) |
Author: Stefan Schwarzer (sschwarzer) |
Date: 2003-04-15 08:01 |
| 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. |
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| msg15415 - (view) |
Author: Walter Dörwald (doerwalter) * |
Date: 2003-04-15 10:01 |
| 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. |
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| msg15416 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2003-04-15 10:40 |
| 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. |
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| msg15417 - (view) |
Author: Facundo Batista (facundobatista) * |
Date: 2005-01-15 17:50 |
| 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 |
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| msg15418 - (view) |
Author: Stefan Schwarzer (sschwarzer) |
Date: 2005-01-28 16:44 |
| Logged In: YES user_id=383516 Hi Facundo The problem still exists in both Python 2.3.4 and 2.4. A possible test case is: import inspect import unittest class TestIsclass(unittest.TestCase): def test_instance_with_getattr(self): class Cls: def __getattr__(self, name): return "not important" obj = Cls() # obj is not a class self.failIf(inspect.isclass(obj)) |
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| msg15419 - (view) |
Author: Facundo Batista (facundobatista) * |
Date: 2005-05-30 19:15 |
| Logged In: YES user_id=752496 Don't know yet if it's a bug or not, but in Py2.4.1 inspect.isclass() is still returning True in these cases... |
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| msg15420 - (view) |
Author: Raymond Hettinger (rhettinger) * |
Date: 2005-08-24 05:25 |
| Logged In: YES user_id=80475 Ping, do you have a few minutes to look at this one and make sure its the right thing to do. |
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| msg15421 - (view) |
Author: Baiju M (baijum81) |
Date: 2006-09-09 13:14 |
| Logged In: YES user_id=565450 Due to this bug, 'pydoc modulename' is not working. pydoc tries to access __name__ attribute of classes, so it raises attribute error. (actually it is not a class, but an instance only). So please increase the priority of this bug. And this case is also not working (same issue): class X: __bases__ = () x = X() |
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| msg57860 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2007-11-26 23:13 |
| Obviously Ping isn't listening, so waiting for him is not productive. Looking at the issue more, I can't really see a bug in inspect -- it's the class definitions that are broken. So closing as "rejected". > Due to this bug, 'pydoc modulename' is not working. Can you be more specific? I can't reproduce this. > And this case is also not working (same issue): > > class X: > __bases__ = () > > x = X() Again, this is just a malformed class. |
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