Context manager getattr test.

gistfile1.txt

# Python 2.5, 2.6 runs okay.
# Python 2.7:
#
# Traceback (most recent call last):
#   File "test.py", line 33, in <module>
#     with cm2:
# AttributeError: __exit__

from __future__ import with_statement

class CM1(object):
    def __enter__(self):
        print '__enter__'
        return self
    def __exit__(self, *args):
        print '__exit__'

class CM2(object):
    def __init__(self, inner):
        object.__setattr__(self, '_inner', inner)
    def __setattr__(self, name, value):
        setattr(self._inner, name, value)
    def __getattr__(self, name):
        return getattr(self._inner, name)

cm1 = CM1()

with cm1:
    print 'CM1'

cm2 = CM2(cm1)

with cm2:
    print 'CM2'