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PEP 484: Type Hints

This GitHub repo is used for three separate things:

- The issue tracker is used to discuss PEP-level type system issues.

However,

[typing-sig](https://mail.python.org/mailman3/lists/typing-sig.python.org/)

is more appropriate these days).

- A copy of the `typing` module for older Python versions (2.7 and

3.4) is maintained here. Note that the canonical source lives

[upstream](https://github.com/python/cpython/blob/master/Lib/typing.py)

in the CPython repo.

- The `typing_extensions` module lives here.

Workflow

* The typing.py module and its unittests are edited in the `src`

subdirectory of this repo. The `python2` subdirectory contains the

Python 2 backport.

Workflow for PyPI releases

* Run tests under all supported versions. As of May 2019 this includes

2.7, 3.4, 3.5, 3.6, 3.7.

* On macOS, you can use `pyenv <https://github.com/pyenv/pyenv>`_ to

manage multiple Python installations. Long story short:

* ``xcode-select --install``

* ``brew install pyenv``

* ``echo 'eval "$(pyenv init -)"' >> ~/.bash_profile``

* Open a new shell

* ``pyenv install 3.5.3``

* ``pyenv install 3.4.6``

* (assuming you already have 2.7.13 and 3.6.1 from Homebrew)

* ``pyenv global system 3.5.3 3.4.6``

* You can use ``tox`` to automate running tests.

* Update the version number in ``setup.py``.

* Build the source and wheel distributions:

* ``pip3 install -U setuptools wheel``

* ``pip2 install -U setuptools wheel``

* ``rm -rf dist/ build/``

* ``python3 setup.py sdist bdist_wheel``

* ``rm -rf build/`` (Works around `a Wheel bug <https://bitbucket.org/pypa/wheel/issues/147/bdist_wheel-should-start-by-cleaning-up>`_)

* ``python2 setup.py bdist_wheel``

* Install the built distributions locally and test (if you

were using ``tox``, you already tested the source distribution).

* Make sure twine is up to date, then run ``twine upload dist/*``.