gistfile1.py

class TestContext(object):
    def __init__(self):
        self.entered = False
        self.exited = False

    def __enter__(self):
        self.entered = True
    def __exit__(self):
        self.exited = True

c = TestContext()
try:
    with c:
        raise Exception('dummy')
except:
    pass

# prints True
print c.entered
# prints False
print c.exited