abc.py:ABCMeta.__instancecheck__ broken for old style classes

[schmir]

BPO	2319

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2008-03-17.16:38:16.349>
created_at = <Date 2008-03-17.10:49:26.302>
labels = ['interpreter-core', 'type-bug']
title = 'abc.py:ABCMeta.__instancecheck__ broken for old style classes'
updated_at = <Date 2008-03-17.16:38:16.332>
user = 'https://bugs.python.org/schmir'

bugs.python.org fields:

activity = <Date 2008-03-17.16:38:16.332>
actor = 'jyasskin'
assignee = 'none'
closed = True
closed_date = <Date 2008-03-17.16:38:16.349>
closer = 'jyasskin'
components = ['Interpreter Core']
creation = <Date 2008-03-17.10:49:26.302>
creator = 'schmir'
dependencies = []
files = []
hgrepos = []
issue_num = 2319
keywords = []
message_count = 3.0
messages = ['63630', '63631', '63670']
nosy_count = 2.0
nosy_names = ['jyasskin', 'schmir']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue2319'
versions = ['Python 2.6']

[schmir]

The following short program raises an exception:

import UserList

class C:
    pass
   
print isinstance(C, UserList.UserList)

---

exception:
Traceback (most recent call last):
  File "t.py", line 6, in <module>
    print isinstance(C, UserList.UserList)
  File "/home/ralf/py26/lib/python2.6/abc.py", line 120, in
__instancecheck__
    subclass = instance.__class__
AttributeError: class C has no attribute '__class__'

If I use a new style class it works.

[schmir]

I used svn revision 61433.

[jyasskin]

Missed this. It's now fixed by r61438.