[RFC] Which module do we use to check the library version?

Optuna uses three modules to check the library versions, i.e., packaging, pkg_resources and distutils. As mentioned in #1551, packaging is not a standard library, and we need an additional dependency.

Currently, packaging is only used for the deprecation, and maybe we can replace it with distutils and reduce the number of dependencies.

See https://github.com/optuna/optuna/pull/1551#pullrequestreview-455262699 for further details.

[toshihikoyanase]

@hvy Sounds reasonable. I created a PR #1589 to replace the other modules with packaging and labeled it contribution-welcome.

[hvy]

Thank you for the throughout investigation. I agree with “introducing” either pkg_resources or packaging, but don’t have a stronger preference for either, since both seem very ubiquitous (license-wise, they also seem okay). Some argument for packaing could be that it’s somewhat lighter and that setuptools could be overkill for this particular use case.

• https://pypi.org/project/setuptools/#files
• https://pypi.org/project/packaging/#files

Edit: packaging is by the way already required in out setup.py so it would require no additions.