Expert Python Programming - Third Edition

As a function – the contextlib module

Using classes seems to be the most flexible way to implement any protocol provided in the Python language, but may be too much boilerplate for many simple use cases. A module was added to the standard library to provide helpers that simplify the creation of custom context managers. The most useful part of it is the contextmanager decorator. It allows us to provide both __enter__ and __exit__ procedures of the context manager within a single function, separated by a yield statement (note that this makes the function a generator). The previous example, when written with this decorator like would look like the following:

from contextlib import contextmanager @contextmanager def context_illustration(): print('entering ...