This might also give a chance for people with familiarity in that API to mention pain points that you can solve in a new API. We can also probably give you a good sense if the thing you want in a library is something that
Make the library, either as a PR to packaging or as it's own independent
pulling out smaller chunks at a time rather than trying to start right off
I should clarify that we have already implemented a number of these as libraries over the last several months (and I am super familiar with pip's internals by now and I'm sure TP is getting there as well). More on this below probably has multiple things that are dependent on getting split out first This would be super helpful, although there is a decent chance we can make some initial headway on this aspect of it just with the first pass agreement library Basically the entire InstallRequirement model is the single most imported item (in my experience) from pip's internals and it is (almost) never used for installing, but often just for metadata access/normalization/parsing. I reimplemented the parsing logic for pipenv in 'requirementslib' (link below) pulling out a big topic is more likely to meet with success. Be cognizant of what the dependencies are for the feature you want to implement, because if it has dependencies, you'll need to pull them out first before you can pull it out OR you'll need to design the API to invert those dependencies so they get passed in instead We are super cognizant of that aspect as I am pretty sure we are hitting this wall in a full (nearly) pip-free reimplementation of all of the pipenv internals from the ground up, including wheel building/installation, but we basically had to start by calling pip directly, then slowly reimplement each aspect of the underlying logic using various elements in distlib/setuptools or rebuilding those. Since you mentioned following along, here's what we're working on right now: https://github.com/sarugaku/requirementslib -- abstraction layer for parsing and converting various requirements formats (pipfile/requirements.txt/command line/InstallRequirement) and moving between all of them https://github.com/sarugaku/resolvelib -- directed acyclic graph library for handling dependency resolution (not yet being used in pipenv) https://github.com/sarugaku/passa -- dependency resolver/installer/pipfile manager (bulk of the logic we have been talking about is in here right now) -- I think we will probably split this back out into multiple other smaller libraries or something based on the discussion https://github.com/sarugaku/plette -- this is a rewrite of pipfile with some additional logic / validation https://github.com/sarugaku/shellingham -- this is a shell detection library made up of some tooling we built in pipenv for environment detection https://github.com/sarugaku/pythonfinder -- this is a library for finding python (pep 514 compliant) by version and for finding any other executables (cross platform) https://github.com/sarugaku/virtenv -- python api for virtualenv creation Happy to provide access or take advice as needed on any of those. Thanks all for the receptiveness and collaboration Dan Ryan gh: @techalchemy // e: dan@danryan.co From: Donald Stufft [mailto:donald@stufft.io] Sent: Wednesday, September 19, 2018 1:52 PM To: Tzu-ping Chung Cc: Distutils Subject: [Distutils] Re: Distlib vs Packaging (Was: disable building wheel for a package) My general recommendation if you want a Python implementation/interface for something pip does, is: - Open an issue on the pip repository to document your intent and to make sure that there is nobody there who is against having that functionality split out. This might also give a chance for people with familiarity in that API to mention pain points that you can solve in a new API. We can also probably give you a good sense if the thing you want in a library is something that probably has multiple things that are dependent on getting split out first (for instance, if you said you wanted a library for installing wheels, we'd probably tell you that there is a dependency on PEP 425 tags, pip locations, maybe other that need resolved first) and also whether this is something that should have a PEP first or not. Getting some rough agreement on the plan to split X thing out before you start is overall a good thing. - Create or update a PEP if required, and get it into the provisional state. - Make the library, either as a PR to packaging or as it's own independent library. If there are questions that come up while creating that library/PR that have to do with specific pip behaviors, go back to that original issue and ask for clarification etc. Ideally at some point you'll open a PR on pip that uses the new library (my suggestion is to not bundle the library in the initial PR, and just import it normally so that the PR diff doesn't include the full bundled library until there's agreement on it). If there's another tool (pipenv, whatever) that is looking to use that same functionality, open a WIP PR there too that switches it to using that. Use feedback and what you learn from trying to integrate in those libraries to influence back the design of the API itself. Creating a PEP and creating the library and the PRs can happen in parallel, but at least for pip if something deserves a PEP, we're not going to merge a PR until that PEP is generally agreed on. However it can be supremely useful to have them all going at the same time, because you run into things that you didn't really notice until you went to actually implement it. My other big suggestion would be to e careful about how much you bite off at one time. Pip's internal code base is not the greatest, so pulling out smaller chunks at a time rather than trying to start right off pulling out a big topic is more likely to meet with success. Be cognizant of what the dependencies are for the feature you want to implement, because if it has dependencies, you'll need to pull them out first before you can pull it out OR you'll need to design the API to invert those dependencies so they get passed in instead. I personally would be happy to at a minimum participate on any issue where someone was trying to split out some functionality from pip into a re-usable library if not follow the develop of that library directly to help guide it more closely. My hope for pip is that it ends up being the glue around a bunch of these libraries, and that it doesn't implement most of the stuff itself anymore.