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Diffstat (limited to 'Doc/library/contextlib.rst')
| -rw-r--r-- | Doc/library/contextlib.rst | 20 |
1 files changed, 16 insertions, 4 deletions
diff --git a/Doc/library/contextlib.rst b/Doc/library/contextlib.rst index cf85fcd4b2..dd34c96c8f 100644 --- a/Doc/library/contextlib.rst +++ b/Doc/library/contextlib.rst @@ -18,6 +18,18 @@ Utilities Functions and classes provided: +.. class:: AbstractContextManager + + An :term:`abstract base class` for classes that implement + :meth:`object.__enter__` and :meth:`object.__exit__`. A default + implementation for :meth:`object.__enter__` is provided which returns + ``self`` while :meth:`object.__exit__` is an abstract method which by default + returns ``None``. See also the definition of :ref:`typecontextmanager`. + + .. versionadded:: 3.6 + + + .. decorator:: contextmanager This function is a :term:`decorator` that can be used to define a factory @@ -447,9 +459,9 @@ Here's an example of doing this for a context manager that accepts resource acquisition and release functions, along with an optional validation function, and maps them to the context management protocol:: - from contextlib import contextmanager, ExitStack + from contextlib import contextmanager, AbstractContextManager, ExitStack - class ResourceManager: + class ResourceManager(AbstractContextManager): def __init__(self, acquire_resource, release_resource, check_resource_ok=None): self.acquire_resource = acquire_resource @@ -578,10 +590,10 @@ single definition:: self.name = name def __enter__(self): - logging.info('Entering: {}'.format(self.name)) + logging.info('Entering: %s', self.name) def __exit__(self, exc_type, exc, exc_tb): - logging.info('Exiting: {}'.format(self.name)) + logging.info('Exiting: %s', self.name) Instances of this class can be used as both a context manager:: |