Python packages should declare their dependencies as requirements

[ScottTodd]

_{Discussed first on Discord here}

I'm rewriting our docs and came across https://google.github.io/iree/get-started/getting-started-python#python-setup:

Install packages:

$ python -m pip install --upgrade pip
$ python -m pip install numpy absl-py

Each package should list its dependencies programmatically so we can drop that explicit pip install step in our documentation.

https://stackoverflow.com/questions/6947988/when-to-use-pip-requirements-file-versus-install-requires-in-setup-py and https://packaging.python.org/discussions/install-requires-vs-requirements/ suggest using the install_requires keyword in setup.py to list dependencies a project minimally requires to run correctly.

We use absl-py for flags and logging, mostly in tests but also in some util files. Similar story for numpy. Certain imports (I tested from iree.tf.support import module_utils but there may be others) fail without these dependencies installed.

• I think we could prune the absl-py dep to be test only, or just accept it as required.
• The numpy dep will probably stick.

[ScottTodd]

iree-tools-tf-snapshot also requires tensorflow (or tf-nightly). Probably a similar story for iree-tools-tflite-snapshot and iree-tools-xla-snapshot, but I haven't checked.

[ScottTodd]

I kept the "install packages" prerequisite in the new python bindings docs (tracking issue: https://github.com/google/iree/issues/5456). Would be nice to fix this to keep the docs simple.

[stellaraccident]

I think this has been fixed for a very long time. Closing.

[ScottTodd]

https://google.github.io/iree/bindings/python/#prerequisites still suggests installing

python -m pip install --upgrade pip
python -m pip install numpy absl-py

[allieculp]

@ScottTodd Should we give this a priority if still open? P1/2?

[ScottTodd]

This just needs someone to verify that requirements are set up correctly and then prune the docs. P2/P3.

[aaron-schneider]

Ho there! This bug hasn't been updated in a long time. Good intentions and all, but we're moving this to the backlog. Feel free to bring it back if you think there's a reasonable chance it'll get worked on in the next 6mo!