Issue 7624: isinstance(... ,collections.Callable) fails with oldstyle class instances (original) (raw)

Created on 2010-01-03 19:13 by rgammans, last changed 2022-04-11 14:56 by admin. This issue is now closed.

Messages (7)
msg97175 - (view)	Author: Roger Gammans (rgammans)	Date: 2010-01-03 19:13
The following sequence causes isinstance to raise an exception rather than to return False. >>> class foo: ... pass ... >>> import collections >>> isinstance(foo,collections.Callable) True >>> isinstance(foo(),collections.Callable) Traceback (most recent call last): File "", line 1, in File "/usr/lib/python2.6/abc.py", line 131, in __instancecheck__ return (cls.__subclasscheck__(subclass) or File "/usr/lib/python2.6/abc.py", line 147, in __subclasscheck__ ok = cls.__subclasshook__(subclass) File "/usr/lib/python2.6/_abcoll.py", line 117, in __subclasshook__ if any("__call__" in B.__dict__ for B in C.__mro__): AttributeError: class foo has no attribute '__mro__' >>>
msg98516 - (view)	Author: Florent Xicluna (flox) *	Date: 2010-01-29 16:26
Confirmed with all others "isinstance(..., collections.Hashable)" and similar. According to the documentation, we might expect the same behavior as for new-style class.
msg98517 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2010-01-29 17:19
Well the fix is easy for old-style classes, since we just have to use hasattr(obj, '__call__') in that case.
msg98522 - (view)	Author: Florent Xicluna (flox) *	Date: 2010-01-29 18:38
Wow, critical issue, are you sure? Here is the patch, with tests. IMO, the tests may be ported to 3.x.
msg98524 - (view)	Author: Antoine Pitrou (pitrou) *	Date: 2010-01-29 18:46
"subtype == _InstanceType" can probably be replaced with "subtype is _InstanceType". Otherwise, the patch looks good to me.
msg98525 - (view)	Author: Florent Xicluna (flox) *	Date: 2010-01-29 18:53
fixed
msg100652 - (view)	Author: Florent Xicluna (flox) *	Date: 2010-03-08 15:35
Fixed in r78800. Additional tests backported to 3.x.