[issue14671] isinstance(obj, object) returns True for _old style_ classes

[Q]

New submission from Q <abonent at gmail.com>:

$python
Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56) 
[GCC 4.4.3] on linux2
>>> class Old: pass
>>> class New(object): pass
>>> o = Old()
>>> n = New()
>>> isinstance(o, object)
True

This is it, basically. Is it a bug or a feature?

More tests :

>>> isinstance(o, Old)
True
>>> isinstance(o, New)
False
>>> isinstance(n, Old)
False
>>> isinstance(o, int)
False

Please note that some unimportant output was deleted from above.

PS. If this is a feature, how do I detect an old-style class then ?

----------
components: Interpreter Core
messages: 159351
nosy: thread13
priority: normal
severity: normal
status: open
title: isinstance(obj, object) returns True for _old style_ classes
type: behavior
versions: Python 2.6

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue14671>
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