refactor setup.py to setup.cfg

[bjlittle]

🚀 Pull Request

Description

This PR rationalises the setup.py into the setup.cfg.

As a justification for this, see this setuptools advise on Transitioning from setup.py to setup.cfg and Transitional Note i.e., the setuptools devs are pushing the community to use setup.cfg rather than setup.py.

Although, note that a minimal setup.py is still required if your project requires to perform a pip install --editable, see setuptools setup.cfg-only projects.

Note that, we've now unified all the PyPI requirements under setup.cfg and users have the option to install dependencies as they need i.e.,

• pip install iris[docs]
• pip install iris[test]
• pip install iris[all]
• pip install iris[docs,test]

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Consult Iris pull request check list

[pp-mo]

Just taking a quick initial look here + wanting to make a more general point :
I'm disappointed that setup.py wasn't simplified still more.
Much of the remaining fuss is to provide the 'custom commands' from setup.py.
Is there now a "better way" for those ?

[bjlittle]

Just taking a quick initial look here + wanting to make a more general point :
I'm disappointed that setup.py wasn't simplified still more.
Much of the remaining fuss is to provide the 'custom commands' from setup.py.
Is there now a "better way" for those ?

@pp-mo At his moment in time, not that I know of... but this PR is certainly a step in the right direction IMHO

If and when building extensions and custom commands is possible outside setup.py, then I'd hope that is additive to the changes proposed here.

[trexfeathers]

Great idea @bjlittle! Some suggestions for you.

[bjlittle]

@trexfeathers @jamesp Awesome, thanks!

BTW I tested this PR successfully with the following:

• python setup.py sdist bdist_wheel
• pip install --no-deps --editable .
• pip install .
• pip install .[docs]
• pip install .[test]
• pip install .[docs,test]
• pip install .[all]