https://github.com/vdmit11/sentinel-value

Sentinel Values - unique global singleton objects, akin to None, NotImplemented and Ellipsis.
https://github.com/vdmit11/sentinel-value

developer-tools missing-values pep661 python sentinel sentinel-value sentinels singleton typing utils

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Sentinel Values - unique global singleton objects, akin to None, NotImplemented and Ellipsis.

• Host: GitHub
• URL: https://github.com/vdmit11/sentinel-value
• Owner: vdmit11
• License: mit
• Created: 2021-10-27T21:14:47.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-02-08T02:17:36.000Z (about 3 years ago)
• Last Synced: 2025-09-01T03:14:53.496Z (7 months ago)
• Topics: developer-tools, missing-values, pep661, python, sentinel, sentinel-value, sentinels, singleton, typing, utils
• Language: Python
• Homepage:
• Size: 237 KB
• Stars: 1
• Watchers: 1
• Forks: 1
• Open Issues: 2
• Metadata Files:
  • Readme: README.rst
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

          
sentinel-value

==============

|pypi badge| |build badge| |docs badge|

``sentinel-value`` is a Python package, that helps to create `Sentinel Values`_ -

special singleton objects, akin to ``None``, ``NotImplemented`` and  ``Ellipsis``.

It implements the ``sentinel()`` function (described by `PEP 661`_),

and for advanced cases it also provides the ``SentinelValue()`` class (not a part of `PEP 661`_).

.. _`Sentinel Values`: https://en.wikipedia.org/wiki/Sentinel_value

.. _`PEP 661`: https://www.python.org/dev/peps/pep-0661

Usage example:

.. code:: python

  from sentinel_value import sentinel

  MISSING = sentinel("MISSING")

  def get_something(default=MISSING):

      ...

      if default is not MISSING:

          return default

      ...

Or, the same thing, but using the ``SentinelValue`` class

(slightly more verbose, but allows to have nice type annotations):

.. code:: python

  from typing import Union

  from sentinel_value import SentinelValue

  class Missing(SentinelValue):

      pass

  MISSING = Missing(__name__, "MISSING")

  def get_something(default: Union[str, Missing] = MISSING):

      ...

      if default is not MISSING:

          return default

      ...

Links

-----

- Read the Docs: https://sentinel-value.readthedocs.io

- GitHub repository: https://github.com/vdmit11/sentinel-value

- Python package: https://pypi.org/project/sentinel-value/

.. |pypi badge| image:: https://img.shields.io/pypi/v/sentinel-value.svg

  :target: https://pypi.org/project/sentinel-value/

  :alt: Python package version

.. |build badge| image:: https://github.com/vdmit11/sentinel-value/actions/workflows/build.yml/badge.svg

  :target: https://github.com/vdmit11/sentinel-value/actions/workflows/build.yml

  :alt: Tests Status

.. |docs badge| image:: https://readthedocs.org/projects/sentinel-value/badge/?version=latest

  :target: https://sentinel-value.readthedocs.io/en/latest/?badge=latest

  :alt: Documentation Status