I best way this was explained to me was to keep your unversioned dependencies in setup.py and keep developing and testing against latest. Then when you release,

I best way this was explained to me was to keep your unversioned dependencies in setup.py and keep developing and testing against latest. Then when you release, requirements.txt should be a result of the build (not an input) which says "these versions work, this is how you install this release". It makes more sense for an application than for a library, but I think making that the primary distinction only adds confusion. All that said, I have no clue what Pipfile is adding. The rationale appears to be that people sometimes don't use requirements.txt properly? Can one of the very enthusiastic commentators explain their enthusiasm?