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typing_extensions

The typing_extensions module provides a way to access new features from the standard library typing module in older versions of Python. For example, Python 3.10 adds typing.TypeGuard, but users of older versions of Python can use typing_extensions to use TypeGuard in their code even if they are unable to upgrade to Python 3.10.

If you contribute the runtime implementation of a new typing feature to CPython, you are encouraged to also implement the feature in typing_extensions. Because the runtime implementation of much of the infrastructure in the typing module has changed over time, this may require different code for some older Python versions.

typing_extensions may also include experimental features that are not yet part of the standard library, so that users can experiment with them before they are added to the standard library. Such features should ideally already be specified in a PEP or draft PEP.

typing_extensions supports Python versions 3.7 and up.

Versioning scheme

Starting with version 4.0.0, typing_extensions uses Semantic Versioning. The major version is incremented for all backwards-incompatible changes.

Workflow for PyPI releases

  • Ensure that GitHub Actions reports no errors.

  • Update the version number in typing_extensions/pyproject.toml and in typing_extensions/CHANGELOG.

  • Make sure your environment is up to date

  • git checkout master

  • git pull

  • python -m pip install --upgrade build twine

  • Build the source and wheel distributions:

    • cd typing_extensions
    • rm -rf dist/
    • python -m build .
  • Install the built distributions locally and test (if you were using tox, you already tested the source distribution).

  • Run twine upload dist/*.

  • Tag the release. The tag should be just the version number, e.g. 4.1.1.

  • git push --tags