gistfile1.txt

>>> from contextlib import contextmanager
>>> @contextmanager
... def foobar(baz):
...     print "Before"
...     yield
...     print "After"
... 
>>> with foobar(0):
...     print "Doing stuff"
...     raise Exception
...     print "Done stuff"
... 
Before
Doing stuff
Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
Exception
>>> 

In [12]: class Foo(object):
....: def init(self): pass
....: def enter(self): print "ENTER"
....: def exit(self, type, value, traceback): print "EXIT"

In [17]: with Foo():
print "hiiii"
raise Exception
....: print "BYE"
....:
ENTER
hiiii
EXIT