Example of use of `contextlib.contextmanager`.

contextmanager_example.py

from time import sleep
def setup():
    print 'setup'


def cleanup():
    print 'cleanup'


from contextlib import contextmanager

@contextmanager
def manage_resource():
    setup()
    yield
    cleanup()


with manage_resource():
    sleep(5)


with manage_resource():
    1/0  # Note that cleanup is not called when an exception is raised.


@contextmanager
def manage_resource_correctly():
    setup()
    try:
        yield
    finally:
        cleanup()


with manage_resource_correctly():
    sleep(5)


with manage_resource_correctly():
    1/0  # Now cleanup is called in the finally block.